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By Frederick C. Trutt, Jeffery L. Kohler, Joseph Sottile

Condition-based maintenance (CBM) of industrial equipment is generally recognized as being the most cost-effective means for improving equipment availability. However, prerequisite to successful implementation of CBM is a reliable detector of failing components. One such detector, termed the effective negative-sequence impedance, had previously been identified as an indicator of induction motor stator winding degradation. However, a limitation of this detector is that it does not change in a predicable manner under certain motor operating conditions. This paper presents an experimental investigation of an improved technique for on-line detection of induction motor stator winding degradation. The paper begins with a brief description of the detectors, followed by a detailed description of the experimental setup, the experiments conducted, and results.

By E. W. Dean

In the early winter of 1919 the Pittsburgh petroleum laboratory of the Bureau of Mines undertook the work of testing fuel oil samples representing purchases of the United State Shipping Board for ships sailing from the port of New York. fuel oil was, at this time, being bought on a contract which involved specifications issued by the United States Navy under dace of October 2, 1920 (See Bulletin 1, Oil Division, U. S. Fuel Administration.)The object of the Bureau of Mines in undertaking this inspection work was twofold. (1) The Bureau was in position to give, and the Shipping Board needed, reliable laboratory service for checking the quality of the fuel oil purchased, the value of which ran into millions of dollars for,year's supply. (2) It was believed, and later demonstrated, that the existing specifications did not insure the obtaining of a reliably satisfactory quality of oil.The objection to the specifications concerned the employment of a clause limiting the gravity of the oil. The inadequacy of gravity specifications for several types of petroleum products has long been recognized, and there was every reason to reason to believe that they were no more desirable for fuel oil than for gasoline, kerosene, or lubricating oil. A first and obvious objection was the fact that it is somewhat difficult to make accurate gravity tests on ""heavy"" residuum fuel oils. (The Bureau found it necessary to employ or such tests a rather tedious procedure involving the use of a picnometer and an accurate balance, as the simpler methods, employing hydrometer or displacement balance, proved unreliable in a large proportion of cases.) A second and more important objection was that gravity tests, even when accurately made, do not provide a reliable index of the actual quality of the oil.

Feb 1, 1921

By E. D. Gardner

"The Bureau of Mines receives many inquiries concerning favorable areas in which to prospect for gold, procedure to be followed, equipment required, and allied subjects. This circular has been prepared for use in reply to these inquiries.Interest in gold mining and prospecting for gold remains steady. From time to time many people take to the field to search for new gold deposits. A large percentage of them have had no previous experience in prospecting for lode gold; this paper has been written with the hope that it might assist these newcomers.A majority of the metal mines in the United States have been discovered by qualified prospectors who were searching for valuable minerals at the time. Chance, however, always has played a large part in finding mineral deposits. Some of the discoveries of the past were made by men on other errands, such as rounding up burros or hunting game. Accidental discoveries of ore bodies have been made in building roads and trails and in excavating for mine struc¬tures. Evidence of ore has been brought to the surface by burrowing animals and by ants; gold found in the craws of fowl has led to discoveries of deposits. Important discoveries have been made by men who had no knowledge of rocks or minerals; on the other hand, many ore bodies have been found by experienced prospectors, sometimes after hundreds of untrained men had already passed over the ground.The prospector who carries on his work diligently and intelligently is of course more likely to be rewarded for his efforts than the lazy or unintelligent worker; nevertheless, it is obvious that if valuable deposits are not present at the place being prospected none will be found. Conscientious and painstaking efforts to trace gold to its source usually disclose nothing more valuable than some narrow, unworkable seams; however, many deposits that were developed into profitable mines were found by this method of prospecting. Although some prospectors have made several lucky strikes, many others have spent their working lives searching for gold without finding anything worth while. Probably only one prospector out of several thousand ever finds anything worth developing. Moreover, only 1 out of every 300 or 400 properties developed becomes a profitable mine.Prospecting was begun in the Western States in the fifties as the miners looked for the source of gold found in placers. The search for gold has been continuous since that time; the number of prospectors in the field at any one time, however, has varied greatly. Except in some desert regions, practicallyall of the placer fields now being worked were discovered by old timers; more-over, most of the important gold districts were found by early prospectors. Important discoveries of lode mines, however, have been made from time to time. Most of the area in the mining regions of the West has been searched many times by prospectors, and nearly all of the easily found deposits have been located, but it is reasonable to expect that new gold mines will continue to be found. Most of the future discoveries undoubtedly will be of deposits that do not outcrop. Prospecting for such deposits requires considerable digging.Several important discoveries were made in 1934. One of these, the Rogers-Gentry gold mine at the edge of Antelope Valley in Los Angeles County, Calif., was found by an experienced prospector on an old patented homestead a number of miles from the nearest producing mine. The initial discovery at this mine was an iron-stained, decomposed, silicous limestone outcrop, with no vein structure evident at the surface, near a small, barren quartz outcrop and a water seep. Another discovery, the Silver Queen gold mine, in the same general region and near Mojave, Calif., was found by an experienced miner on an open fraction 400 by 1,400 feet in size between two old properties that were thought to have been worked out years ago. The Silver Queen discovery was made as the result of finding a"

Feb 1, 1950

By John T. Aydelotte, Martin J. Gavin

" Oil shale contains little or no oil as such , but it contains an organic material from which oil may be produced by destructive distillation" . This statement , or others conveying the same meaning, appears in many popular and techni cal articles on oil shale . It is based on the belief that the ordinary solvents of petroleum have but little action on the organic substances contained in oil- yielding shales , although on distillation these same shales may yield upwards of 50 gallons of crude shale oil per ton . A 50 - gallon shale thus yields by distillation 18.73 per cent of its weight as oil ( assuming the specific gravity of the oil to be 0.900 ) , although only a relatively small part of this can be recovered by extraction with such solvents as chloroform , carbon tetrachloride , and the like . In the course of certain experiments designed to determine the solubilities of different shales after they had begun to yield oil by distillation , it was found desirable to determine the quantity dissolved from certain unheated shales by various solvents , at or near the boiling points of these solvents . The method used and results obtained are presented below. These experiments were made in connection with the oil - shale investigations being conducted by the U. S. Bureau of Mines , in cooperation with the States of Colorado and Utah .

Jan 1, 1922

By Roy C. Bartholomae

This U.S. Bureau of Mines study found that the performance of the active noise cancellation hearing protector in a reverberant field was mixed. The performance varied when the conditions changed from ideal to nonideal. The active noise cancellation (ANC) component provided substantial additional noise reduction from 125 to 500 Hz for all testing conditions (broadband noise or pure tones both with and without safety glasses). While the ANC under ideal conditions provided additional attenuation from 500 Hz and below, under nonideal pink noise conditions the ANC amplified noise below the 125-Hz third octave band. There was a middle band of frequencies at which the ANC amplified noise levels ranging from 630 to 4,000 Hz. The results for pure tones showed that attenuations were higher but that they followed the same general trend.

Jan 1, 2010

By Robert S. Sanford

The Broughton and Ring magnetite deposits in Essex County, N. Y., are thought to be in a mineralized belt that extends from the Lake Sanford mining district to Lake Champlain and passes through the Mineville district. The country rook is syenite-gneiss, similar to that in the Mineville area. The Bureau of Mines conducted a vertical magnetometer survey of the area. On the Broughton properties there are no indications, magnetically, of magnetite in any degree of concentration. 'On the ding properties a number of sharp, localized magnetic anomalies were observed. One core-drill hole was bored to a, depth of 48.3 feet, also, to test one of the strongest anomalies. The field work was in progress from December 1943 to July 1944. Although no iron ore was intersected by' the drill hole, it showed that the amphibolite rook, at a depth of 6 to 100 feet below the surface, contained enough magnetite and iron sulfides to account for the anomalies recorded by the magnetometer survey.

Jan 1, 1949

By R. V. Ramani, C. B. Manula, A. Owili-Eger

All the input data required to operate the ventilation simulator except the title, are entered with I10 or F1O.O formats. The title is entered with (18A4) format. The floating points are designated by (FP) and the integers by (INT)

Jan 1, 1975

By Ray J. Holmquist

"INTRODUCTION The Copper King or Red River copper mine was examined on December 13, 1942, by the Bureau of Mines at the request of Richard Kelly of Santa Fe, N. Mex. The examination was made to determine whether the expenditure of funds for rehabilitation work necessary to make the workings accessible for examination would be warranted.As a favorable report was made, the workings of the Copper King mine were opened and sampled under the direction of the author. The portal of the Copper King adit was opened first. Considerable rehabilitation was necessary in the first 50 feet of the workings, but the remainder of the drifts and crosscuts were sufficiently open to permit surveying and sampling.An attempt was made to open the Waterbury atilt, which was reported to be about 30 feet east of the Copper King portal, and to crosscut the ore body nearly to its southern border. However, slide rock and mine dumps had completely obscured the portal of this adit, and no opening into it could be found or made.Work on the project was started on September 27 and vas completed on November 6, 1943."

Apr 1, 1947

By James L. Hendrix

A study was made of the United States Bureau of Mines' chlorine-oxygen leaching process for complex sulfide concentrates. The investigation sought to determine the kinetic order and IT mechanisms involved in the reactions betweens sphalerite, and galena with chlorine. The influence of copper on the extraction rates was also studied. It has been shown the rates of reaction of chlorine in aqueous solutions with sphalerite and galena are both zero order at 373K with the rate limiting step being the chemical reaction. Addition of cupric chloride increased the extractions of both lead and zinc.

Jan 1, 1980

By Carlton E. Brown, William P. Yant

"INTRODUCTION Direct visual microscopic determination of particle-size distribution and number concentration of atmospheric dust is time-consuming and trying to the eyes. By using the microscope to project images of the particles at high magnification onto a screen much of the eyestrain can be eliminated and particle-size distribution results obtained with less effort and at a considerable saving in time. It also permits simultaneous observation of the images by more than one person. Microprojection requires no more skill and very little more apparatus than is required in the use of the microscope. Anyone familiar with the microscope should be able to obtain as perfect images on the projection screen as in direct visual microscopy since the same laws and limitationsThe theory and practice of microprojection are described in detail in texts. 5/6/ The procedure has been used and found to be satisfactory for measuring the particle-size distribution of sub-sieve-size substances, such as pigments and powder 7/8/ in the same size range as that of atmospheric dust. The Bureau of Mines has used the microprojector and found it to be quite satisfactory for (1) the determination of the number concentration of atmospheric dust R.I. 3289 in samples collected by the Owens jet dust counter; (2) particle-size distribution in samples of atmospheric dust collected by the Owens jet dust counter and by the electric precipitator; and (3) the particle-size distribution of dusts, blood cells, bacteria, and pollen. Work is in progress at this Bureau on the use of the microprojector in counting impinger samples. The use of different kinds of illumination, such as reflected (dark field), polarized, monochromatic, and ultraviolet, in the projection of images of atmospheric dust particles is being considered."

Oct 1, 1935

By R. C. Buehl

[Improvements in refractories for high-temperature service have made possible the use of higher temperature in many processes. Consequently, it sometimes is desirable to use gases heated above 1,600° F., and for moderate rates of gas flow, there gases can be heaters best with pebble heaters. Pebble heaters of the stationary-bed type in which the chanber was lined with mullite brick and pebbles of pure alumina served as the heat-exchange medium have been used recently to heat the air blown into an experimental blast furnace4/ These pebble heaters worked well and made it possible to use air temperature up to 2,500° F. at the tuyere of the furnace. Since little has been published on this type of gas heater, a review of the construction on employed and operating data should assist in selecting applications and designing units.]

Jan 1, 1953

By L. C. IlsLey

From time to time the Bureau of Mines has issued publications dealing with the various classes of explosion-proof mining machinery that have been tested and approved as permissible for use in mines having atmospheres that may become inflammable by reason of the inadvertent presence of gas or dust. These publications are confined almost entirely to description of the features contributing directly or indirectly to the prevention of explosion or shock hazards, and are intended to give inspectors, safety engineers, and others already familiar with the general safety requirements more detailed information on the safety features of the design of a particular machine. As a background for papers describing permissible machines and to avoid the necessity of duplicating descriptions of methods of conducting investigations and tests of such machinery, Bureau of Mines Bulletin 305, Inspection and Testing of Mine-Type Electrical Equipment for Permissibility, was pub¬lished in 1929. Three bulletins giving detailed descriptions of the three most numerous types of machines have been issued, viz., Bulletin 313, Permissible Storage-Battery Locomotive and Power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 392, Permissible Coal-Cutting Equipment.

Jan 1, 1937

Improve the safety and comfort of operators of large mining equipment. Approach Develop an improved driver restraint system that is easy to use, reliable, and cost-effective, while providing increased protection in the event of a collision or rollover. The Novel Restraint System There are several problems associated with conventional lap-belt type restraint systems. Among these are: restriction of movement, lack of comfort, and fear of entrapment. Standard seatbelts become dirty and oily from lying on the vehicle cab floor and can ruin a driver's clothes. Some haulage equipment may not even have seatbelts available to drivers since they are sometimes removed during maintenance activities or as a result of vandalism. Recognizing a need to address such problems by providing a more acceptable means of driver restraint, the Bureau of Mines designed and fabricated a novel vest-type restraint system. The vest is designed to be worn during a driver's 8-hour shift and would be issued much like safety glasses, hard hats and safety shoes, thus becoming part of the operator's individual protective equipment and assuring that each vehicle has a restraint system when in operation. The vest-

Jan 1, 1985

By David S. Yantek

A-weighted sound levels around vibrating screens in coal preparation plants often exceed 90 dB(A). The National Institute for Occupational Safety and Health (NIOSH) is actively developing noise controls to reduce noise generated by horizontal vibrating screens. A 121-microphone, 3.5-meter-diameter array was used to perform beamforming to determine locations of significant noise radiation on the screen. Below about 1 kHz, the screen body was found to be the most significant noise source. The beamforming contour maps showed several key locations on the sides of the screen and the feedbox are the most significant contributors. Operating deflection shape (ODS) analysis was used to examine the screen behavior under actual operating conditions. This information is helpful in determining how to modify the screen body to reduce the noise radiated by the screen below 1 kHz. The analysis showed modal vibration patterns on the sides and feed box were the main contributors to noise. The results show several areas on the screen sides and feedbox that can be modified to reduce noise.

Jan 1, 2009

By E. D. Gardner

Humphreys Gold Corporation of Denver, Colo., was conducting a successful placer operation in 1936 on North Clear Creek about 6 miles below Blackhawk in Gilpin County, Colo. About 3,000 cubic yards of gold-bearing gravel are dug daily (September. 1936) by two draglines and a power shovel. The gravel is screened in a portable washing plant; the trommel oversize is discarded, and the undersize is pumped to a gold-saving plant. The gold is caught in riffles in sluice boxes. The total cost of mining is about 20 cents per cubic yard. The mine is in a narrow canyon at an altitude of 7,200 feet. The Blackhawk-Central City branch of the Colorado & Southern RR. runs over the property. Freight platforms for receiving supplies were moved as the workings advanced. The workmen reached the mine on a speeder that ran on the railroad tracks from a point on the automobile highway (U. S. 40) on Clear Creek near the bottom of Floyd Hill, about 5 miles distant. The mine is 36 miles by road and speeder, or 30 miles by rail, from Denver.

Jan 1, 1937

By C. E. Reistle

[In producing crude oils of paraffin base and of mixed base the producer is often confronted with the problem of preventing and removing paraffin that settles out of oil and accumulates in the well. This paraffin consists of heavy waxes with some sand and asphalt, and varies in. consistency from a soft semifluid wax to hard gummy wax. This problem is by no means a new one as troubles have been encountered with it since the earliest days of the industry. However, with the discovery of the panhandle, Texas, field and other large fields in which extensive troubles have been encountered, the problem has assumed added importance. In new fields the most serious trouble with paraffin is in the flowing wells the paraffin accumulates in the casing and tubing of such wells and unless removed will completely plug the well. This condition also develops in wells which are produced by gas lift, and often presents a serious problem when, this method of producing the oil is used. In older fields paraffin is also deposited on the face of the producing sand that on the walls of the hale or within the interstices of the sand near the hole, and this materially affects the amount of oil that can enter the well.]

Jan 1, 1927

By Kevin Michael, David C. Byrne

In previous issue of Spectrum (October 1999, 16/4), a system of measuring the attenuation provided by insert-type hearing protectors was described, That report described experiences using the FitCheck (Michael & Associates, Inc.) system in a pilot project involving the steel industry during 1998.[ ]

By E. G. King, W. W. Weller

Low- temperature heat capacity measurements of muscovite were made in the temperature range from 50° to 298 ° K. The entropy at 298.15 ° K was evaluated as S298.15 = 69.0 ± 0.7 cal /deg mole .

Jul 1, 1960

By G. R. Palmer

The Bureau of mines evaluated the elution of uranyl carbonate from a strong base resin with a mixed carbonate eluant in a fluidized system. The system consisted of a multiple-compartment ion-exchange (MCIX) elution column with a continuous flow of solution, except for short periods when the resin increments were withdrawn. The exchange of uranyl carbonate from the mill-loaded strong base resin with an eluant composed of 1.0 [M] NaaCOs plus 1.0 [M] NH4HCO3 was studied. The effects of solution flow rate, aqueous-to-resin flow ratio, column diameter, compartment height, initial resin concentration, and column length were examined. The experimental data indicate that for the eluant examined, a resin residence time of 240 minutes is necessary to attain 90-percent elution efficiency. Also provided is a technique for sizing an elution MCIX column form pilot plant experimental data.

Jan 1, 1979

By Erica E. Hall, Robert H. Peters, Charles Vaught, Jon C. Volkwein

Coal workers’ pneumoconiosis is the leading cause of death due to occupational illness among U.S. coal miners. This disease is caused by miners’ exposure to excessive levels of respirable coal mine dust. A personal dust monitor (PDM) has recently been developed to provide near real-time feedback to miners regarding the level of respirable coal dust in the air they breathe. The main objective of this report is to document coal miners’ reactions to this device and how they make use of the information it provides. It summarizes a field study by the National Institute for Occupational Safety and Health that documented the opinions of 30 miners at 4 underground coal mines concerning the use of PDMs.

Jan 2, 2008