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By Rolland L. Blake

The Bureau of Mines investigated the mineralogy, tonnage, and beneficiating characteristics of oxidized (nonmagnetic) taconite iron resources of the Western Mesabi Range as part of its program to insure adequate future domestic mineral supplies. Magnetic taconite currently provides about 95 pct of Mesabi production, but the large tonnages of oxidized taconite between the magnetic deposits will be needed to help meet future domestic demand for iron ore. Three bulk samples that represent large tonnages from the Western Mesabi Range were selected to determine their mineral composition and liberation by light optical microscopy and to test their beneficiating response. This report describes the mineralogy and liberation characteristics of the three samples of the Biwabik Iron-Formation for 26.5 mi (42.7 kID) from Keewatin to Grand Rapids, MN. (Details of response to beneficia-tion were reported previously.) The samples represent mostly material from the Lower Cherty Member of the Biwabik-Iron Formation, although one sample included some Upper Cherty Member. Minerals of all three samples were quartz (chert), hematite, goethite, and minor to trace amounts of magnetite, iron carbonate, and iron silicates. It was concluded that the oxidized taconites of the Western Mesabi Range represent a subeconomic indicated resource that can be selectively mined and beneficiated as a future large source of iron feed for steelmaking.

Jan 1, 1983

By Seth T. Reese

REPORTS received from operating companies by the Bureau of Mines, United States Department of the Interior, indicated marked progress in the reduction of injuries to employees in the coking industry in 1951 as compared with 1950. The fatality rate (0.14) per million man-hours of exposure declined 33 percent and was the second best performance since statistics on the industry were first collected in 1916. The nonfatal-injury rate (10.94), the best since 1940, declined 8 percent and was bettered only in 8 of the past 36 years. The nonfatal rate is based on all injuries resulting in loss of time for more than the remainder of the day on which the injury occurred. The exposure to hazard, as represented by the number of man-hours of work time during the year, was 7 percent higher than in 1950 and, except for the year 1943, was the highest since 1920. The fatality rate for men employed at beehive-coke ovens decreased 16 percent and the nonfatal-injury rate 23 percent, while the man-hours of work time or exposure increased slightly over 16 percent. The fatality and nonfatal-injury rates at byproduct ovens declined 33 and 2 ½ percent, respectively, while the number of man-hours worked increased 6 percent.

Jan 1, 1954

By Shannon Seitz, Qingwen Shi, Junfeng Pan, Shuwen Wang, Brijes Mishra, Shaohong Liu

Delayed coal bursts in deep coal mines have caused significant fatalities and economic losses in recent years. Instead of occurring right around the advancing face, this particular type of coal burst is characterized by its occurrence at a certain distance behind the advancing face. To better understand the mechanism of a delayed coal burst, we used borehole camera, electromagnetic CT, and borehole deformation monitoring device to observe the fracturing and deformation process of an advancing entry’s surrounding coal in the field. Borehole camera detection showed a zonal disintegration phenomenon in the advancing entry’s surrounding coal. Electromagnetic CT detection showed that zonal disintegration developed within 14 days of excavation. Borehole deformation monitoring indicated a deformation rate difference between the intact zone and fractured zones. The deformation rate difference was observed to increase with time and cause increasing elastic energy accumulation in the intact zone. The cumulative elastic energy in the intact zone finally caused a delayed coal burst in the entry. Sensitivity analysis of the cumulative elastic energy was conducted based on a thick-walled model deduced from field detection. The model shows that the smaller thickness of the intact zone brings higher elastic energy in the intact zone. This investigation provides an improved understanding of delayed coal bursts in deep coal mines.

Oct 19, 2021

By Raymond D. Potts

"Minntac is a taconite mining, concentrating and pelletizing operation located near the town of Mountain Iron, Minnesota, U.S.A. It is totally owned and operated by USX Corporation and represents its largest source of domestic iron units. Minntac began producing fluxed pellets in 1988 and has produced both acid and fluxed pellets since then. This paper compares the acid and fluxed pellets produced at Minntac. It reviews modifications that have been made to the plant flowsheet and discusses areas recognized for improvement since the beginning of fluxed pellet production. It also comments briefly on the performance of Minntac fluxed pellets in USX blast furnaces and the future of fluxed pellets at Minntac.IntroductionMinntac was built in three steps with each step designed to produce 6 million long tons of acid pellets per year. The actual production has varied though. Figure I shows the production by year at Mirmtac. Step I began production in 1967, Step 2 in 1972 and Step 3 in 1978. Mirmtac produced 16.5 million tons in 1979 but only 3.5 million tons in 1982 when the facility was shut down for six months because of the lack of demand for pellets. Since the initial start up, Mirmtac has produced over 200 million long tons of pellets. Until 1987, all the pellets produced were ""acid"" pellets. In 1987, equipment to produce ""fluxed"" pellets was installed and tested. In 1988, full scale production of fluxed pellets began."

Jan 1, 1991

By J. P. Connell

The U.S. Bureau of Mines awarded a contract to Morrison-Knudsen, Inc., to evaluate the use of roadheaders in underground mining operations. Road-headers were found to be widely used in mines as construction support units, as development miners, and as stoping machines. However, road-headers were found to have mechanical and electrical problems, to suffer reduced productivity when integrated into the mining cycle, and to create dust problems. Also high capital costs and low utilization and avail-ability cause high amortization costs per ton. This report identifies the roadheader operating problems and offers suggestions for improved mechanical and electrical design as well as manufacturer and owner responsibilities for improved availability. The development of a complex integrated excavation and ground support sys tern is no t warranted until the roadheader itself is made much more reliable.

Jan 1, 1980

By C. Fairhurst

Most of the papers designated as being within the topic of underground storage at this Symposium are concerned with aspects of radioactive waste isolation. Although this is, unquestionably, an important international application of underground storage, and one involving a considerable number of research investigations, the subject of underground storage is indeed much broader. Several major international conferences have been devoted exclusively to it. Applications include storage, under a range of temperatures and pressures, of oil and liquefied petroleum products, compressed air, heat, foodstuffs of various kinds, hazardous and 'nuisance' industrial by-products, and a variety of special applications, both civilian and military - some in use, others proposed. Storage may be in caverns excavated specifically for the purpose, exhausted mines may be adapted for storage or, in some cases, the material to be stored may be injected under pressure into the pore spaces of porous-permeable formations at depth. A variety of rock types and geological environments are used, e.g. excavations in salted or domal salt, where long-term creep closure of the openings is a concern; massive granite, where fluid loss through fissures may be important. Cavities may have spans of several tens of meters, and there is interest in achieving still larger excavations. As would be expected, this breadth of underground storage applications introduces a similarly broad range of questions in rock mechanics and rock engineering. The report will review these questions and recent developments in rock mechanics research, computational procedures, and design applications - and will also discuss the opportunities for a still greater range of applications of underground storage to current industrial and social problems.

Jan 1, 1989

By A. B. Cecala, G. W. Klinowski

Introduction The US Bureau of Mines has designed and evaluated total mill ventilation systems (TMVS) at two mineral-processing operations. Both systems have proven proficient at cost-effectively reducing respirable dust levels throughout the mills. An 11.8-m3/sec (25,000-cfm) system installed at a clay-processing mill provided about 10 air changes per hour (acph). This system reduced respirable dust concentrations by about 40% throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 23.6 and 47.2 m3/sec (50,000 and 100,000 cfm) of ventilation to the mill building, corresponding to 17 and 34 acph. Average millwide respirable dust reductions were 36% and 64%, respectively. This work was done to determine general guidelines and design criteria for operations that may be interested in implementing TMVS. TMVS should be designed to draw clean make-up air in near the base of the mill. This air provides general purging and may clear some dust-laden areas throughout the mill structure. It is discharged at or near the top of the structure. Without the TMVS, dust can exit the building through open doors, windows, etc. and contaminate outside plant workers. This dust can also be recirculated back into the mill building causing additional contamination problems. TMVS is not a stand-alone system. It is a supplemental technique to assist other localized dust control systems (Mody et al., 1987). Testing Total mill ventilation systems were evaluated at two processing operations. For both tests, the primary goal was to determine the reduction in respirable dust throughout the structure. Test site No. 1. The first evaluation was performed at a clay-crushing and screening mill in New York. The mill's base dimensions were 39.6 x 9.8 m (130 x 32 ft), giving a volumetric capacity of 4250 m3 (150,000 cu ft). The TMVS was designed to provide 12 m3/sec (25,430 cfm) of ventilation air to the mill, representing about 10 acph. This was accomplished by three 4 m3/sec (8475 cfm) roof-powered exhaustors that were evenly spaced across the roof. Three wall louvers provided inlets for make-up air at the mill's base. Two evaluations were performed at this mill. The first occurred for two days in December when outside air temperatures ranged from -12.2° to 4.4° C (10° to 40° F). Temperatures with the wind chill factor dropped as low as -34° to -40° C (-29 to -40° F) during the early morning. The second evaluation was in April when outside air temperatures ranged between 10° to 26.7° C (50° to 80° F). These two evaluations verified the effectiveness of TMVS in lowering respirable-dust concentrations throughout the mill. Gravimetric-sampler respirable-dust concentrations in December ranged from 0.22 to 2.39 mg/m3 under normal conditions, compared to 0.13 to 1.55 mg/m3 with TMVS. In April, respirable dust concentrations ranged from 0.29 to 4.84 mg/m3 under normal conditions compared to 0.21 to 2.37 mg/m3 with the system on. TMVS also increased visibility throughout the mill building. Dust reductions for gravimetric and RAM-I instruments are listed in Table 1. Each value was determined by comparing the average concentration for the entire day of testing for normal and TMVS values. The mean/standard deviation values for gravimetric and RAM-1 results were 42.5/17.6 and 37.1/16.8, respectively.

Jan 1, 1996

By R. P. Maloney

Since mining operations began in 1900, Government geologists and mining men have periodically recorded the presence of the minerals of mercury and antimony in the extensive gold placer deposits near Flat in the Iditarod district of the Yukon River region, Alaska. No serious effort was made to recover the cinnabar contained in the gold placer gravels, and there is no evidence that veins of cinnabar and stibnite exposed in the placer operations (as reported by the Geological Survey) were ever explored or developed. A large monzonitic intrusive, which is the dominant geologic feature of the immediate area, is believed to be the lode source of the valuable minerals in the placer deposits. In contact with the monzonite are argillite and quartzite, metamorphic products from the Cretaceous shales and sandstones.

Jan 1, 1962

By D. B. Lovett

The work described in this report was directed toward identifying and devising methods to minimize the previously observed variability between working level hour exposures and the alpha particle track densities resulting on Track Etch films exposed to mine atmospheres containing radon and radon daughters. The disequilibrium between radon and its daughters was shown to directly affect this Track Etch film calibration factor. The wide range of disequilibrium states possible in mine situations amply explains the variability in the previous tests. A file of published mine atmosphere composition data was compiled and was used, along with atmospheric compositions derived from several theoretical models ref the atmospheric behavior, to evaluate the variability of several dosimeter configurations and concepts. A nonlinear, iterative regression analyse; was formulated that successfully predicted working levels to within 8 to 10% from only the alpha particle activities (Rn, RA, and RaC') data such as are obtainable from Track Etch films over a wide range of disequrlibrium conditions. A model expressing atmospheric concentrations as a function of radon source strength, plate out rate factor, ventilation rate and the fractional re-entry by recoil of previously platted-out daughters was derived and used in the regression program in addition to preparing a set of reference tables and graphs showing the disequilibrium behavior of the atmosphere. Other factors that can affect the Track Etch Film response writ considered and shown to he less crutial than the disequilibrium state. The results of a series of exposures of a dosimeter concept fixture in the Denver Mining Research Center radon chamber air presented and discussed.

Jan 1, 1976

By Stewart L. Toleman, Robert H. Hafner, Irvin R. Kramer

In his paper on the calculation of harden-ability from chemical composition, Gross-mannl discussed the effect of most of the alloying elements used commercially. The purpose of the work reported in this paper was to determine the effect of several other elements on hardenability—arsenic, antimony, beryllium, cobalt, columbium, germanium, tellurium, tin, aluminum, and titanium—and to extend the range of composition of some of the elements studied by Grossmann—chromium, copper, manganese, molybdenum, nickel and silicon. Experimental Methods To determine the effect on hardenability, suitable amounts of the alloying elements were added to experimental heats and the hardenability determined by means of end-quenched hardenability specimens. The steels were melted in a high-frequency induction furnace with a basic crucible, using ingot iron as a base for some of the heats and S.A.E. 1015 for others. The alloying additions were made as ferroalloys or as metal, depending on the alloying element. Hundred-pound heats were split and poured into square, tapered, cast-iron ingot molds with hot tops. Aluminum was not used as a deoxidizer in most of the heats. The ingots were homogenized for 12 hr. at 1260°C. (23oo°F.) and forged into rounds of I½ -in. diameter. These bars were normalized twice from 840°C. (I55o°F.) before machining into Jominy bars. mined in most Cases by samples taken from the end-quench hardenability spedmen. AS suggested by Crafts,2 acid-soluble (8

Jan 1, 1944

By Robert H. Hafner, Irvin R. Kramer, Stewart L. Toleman

In his paper on the calculation of harden-ability from chemical composition, Gross-mannl discussed the effect of most of the alloying elements used commercially. The purpose of the work reported in this paper was to determine the effect of several other elements on hardenability—arsenic, antimony, beryllium, cobalt, columbium, germanium, tellurium, tin, aluminum, and titanium—and to extend the range of composition of some of the elements studied by Grossmann—chromium, copper, manganese, molybdenum, nickel and silicon. Experimental Methods To determine the effect on hardenability, suitable amounts of the alloying elements were added to experimental heats and the hardenability determined by means of end-quenched hardenability specimens. The steels were melted in a high-frequency induction furnace with a basic crucible, using ingot iron as a base for some of the heats and S.A.E. 1015 for others. The alloying additions were made as ferroalloys or as metal, depending on the alloying element. Hundred-pound heats were split and poured into square, tapered, cast-iron ingot molds with hot tops. Aluminum was not used as a deoxidizer in most of the heats. The ingots were homogenized for 12 hr. at 1260°C. (23oo°F.) and forged into rounds of I½ -in. diameter. These bars were normalized twice from 840°C. (I55o°F.) before machining into Jominy bars. mined in most Cases by samples taken from the end-quench hardenability spedmen. AS suggested by Crafts,2 acid-soluble (8

Jan 1, 1944

By S. R. Crane

One Bureau of Mines goal is to minimize the undesirable environmental impacts associated with industrial plants emitting waste gases containing S02. To help meet this goal, a regenerable flue gas desulfurization process was developed. This process, known as the citrate process, uses a buffered weak acid solution to absorb S02 from the waste gas. The absorbed S02 is reacted with H2S to precipitate elemental sulfur and regenerate the solution for recycle. The H2S feedstock for the process, if not otherwise available, may be produced by reacting two-thirds of the recovered elemental sulfur with natural gas and steam. Laboratory investigations and pilot plant operations were conducted by the Bureau to determine if H2S from the natural gas, sulfur, and steam reaction was suitable for the citrate process. The laboratory investigations, in which an H2S generator was integrated with other citrate process operations, provided a basis for design and operation of the pilot plant. The objective of the pilot plant was primarily to provide H2S for the citrate pro-cess pilot plant at the Bunker Hill Co. lead smelter in Kellogg, Idaho. The design capacity of the pilot plant was 0.4 to 1.25 tons of H2S per day. The operation demonstrated that (1) a 77-to 79-dry-volume-percent H2S product could be produced from pilot-plant product sulfur, natural gas, and steam; (2) the product R2S regenerated the SO2-loaded citrate solution; and (3) under certain conditions over 95 percent of the natural gas could be converted to H2S.

Jan 1, 1981

By Daryl R. Tweeton

The Bureau of Mines is investigating possible applications of geophysics to monitor leachate during in situ mining. Tomographic reconstruc-tion of seismic or electromagnetic crosshole data appears applicable. The tomographic program BOMTOM (Bureau of Mines tomography) was written and then used to investigate reconstructions with synthetic travel time data. The calculations confirmed that without constraints, crosshole data do not provide unique solutions. The solution is not determined solely by the data, but is also influenced by the velocity guesses starting the iterative solution procedure. The effectiveness of constraints in combatting nonuniqueness was examined. The requirement that the velocity not vary laterally at the top and bottom of the pixel grid was effective. This constraint is realistic when the top and bottom of the grid represent dry and saturated re-gions, respectively. Limiting the maximum velocity improved reconstructions, but may not be applicable in practice. BOMTOM uses the simultaneous iterative reconstruction technique (SIRT) with straight ray paths. The program is efficient in use of memory, and can be run on a personal computer. A source code in FORTRAN is listed. A source code in BASICA and compiled executable codes in both languages are available from the Bureau's Twin Cities (MN) Research Center.

Jan 1, 1985

By W. L. Dare

This information circular is one of a series published by the Federal Bureau of Mines in which the methods and costs of producing uranium ore on the Colorado Plateau are discussed. This report describes the three largest company-operated uranium mines of Climax Uranium Co. - the G-1, the Mineral Joe, and the Frank No. 1. Climax Uranium Co., a subsidiary of American Metal Climax, Inc., was [corporated] May 11, 1950, just 2 years after establishment of the domestic uranium program by the Atomic Energy Commission. Twenty-five years earlier Arthur H. Bunker, now chairman of the board, American Metal Climax, Inc., organized and operated the U. S. Vanadium Co. at Rifle, Colo.3/ Soon after Climax Uranium Co. was organized, it entered into a contract with the Federal Government to build a uranium-vanadium processing mill in Grand Junction, Colo. Under the contract Climax leased from the Federal Government certain uranium-bearing lands that had been withdrawn from public entry in 1948. From Minerals, Engineering Co. on June 12, 1950, Climax acquired other uranium-vanadium properties on Calamity, Outlaw, and Monogram Mesas in Colorado and on Polar Mesa and in the Yellow Cat area of Utah. To house the milling equipment, Climax leased the old Grand Junction sugarmill building of the Holly Sugar Co. Milling facilities, based on a then new process developed for treating both uranium and vanadium, were completed, and the plant went into production in 1951.

Jan 1, 1959

By Coates D. F, Neil T. J, O&apos

A proper economic analysis of pit slope design must reflect the trade-off between the benefits and the increased risks of slope fail- ure inherent in steeper slope angles. However, no formal framework for a proper analysis existed to date. This paper describes the results of the past four years' effort in which a formal eco- nomic analysis framework was developed and tested through a case study. This framework, in essence, consists of the availability of tested procedures and com- puter programs. The procedures as well as the programs are divided into two broad functional categories; (1) the first category related to assessing the economic benefits and costs associated with various pit slope angles and (2) the second category that determines the overall financial impact which the assessed benefits and costs exert to the mine operator's overall economic stature.

Jan 1, 1977

By R. A. Cattell

The peacetime activities of the Bureau's petroleum and natural-gas program have been reoriented to serve the needs of a national-defense program. When the United Nations sent troops to Korea after the North Korean Army crossed the 38th parallel in the latter part of June 1950, the Bureau's coordinated national program on petroleum and natural gas, with each major project forming an essential member of its framework, was carefully reviewed by those in charge of the work. As a matter of fact, the era of normalcy in which the petroleum and natural-gas research of the Bureau of Mines prospered during the fiscal year 19502/ was no sedative to the need for alertness on a national-defense front. The program, although conducted along peacetime lines in general, was scanned critically and repeatedly during that period to see where - if the need should arise -the emphasis could be shifted from peace to defense or war. Judging from the experience of two wars, it would not be long before the Bureau would be asked to use its trained technical personnel in applying techniques already learned in peacetime research to the requirements of munition and fuel needs of national defense. Near the end of January 1951, petroleum and natural-gas engineers of the Bureau of Mines began a comprehensive study of reservoir conditions in the Canyon Reef fields of Scurry, Borden, and Kent Counties, Tex. This work was preceded by published analyses of crude oils from Scurry County as early as April 1950. Well-informed persons in industry have estimated that these fields hold reserves that will yield 3 to 6 billion barrels of stock-tank oil. Although generally accepted good operating practices have been followed, engineering tests have shown that the natural energy, except in some favorable parts of the reservoir, will not be adequate for obtaining a high percentage of recovery. Correct information regarding the extent and availability of this vast reservoir of hydrocarbons is therefore of great concern to the Petroleum Administration for Defense in carrying out its responsibilities under the Defense Production Act.

Jan 1, 1952

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and non-fatal injuries. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the Mine Safety and Health Administration (MSHA) between 2010 and 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84% involved the workers not using fall protection, fall protection not being provided, or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment, or working near highwalls. In most cases, a single, basic, corrective action (e.g., using fall protection) would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate, and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

Minutes of meeting held at the Moth Hall, Witbank on 13th November, 1969. There were present eleven members: Mr J. Meintjes (in the chair); Messrs I. E. van Aswegen, O. T. Wright, A. W. L. Brereton, A. Bain, J. Brook, P. J. Beukes, C. H. Coxon, B. F. v.d. Merwe, A. C. Hofmeyer, G. E. Carlyon. Six Associate Members: Messrs E. J. Jackson, J. N. H. Pritchard, R. E. Powell, W. Weber, R. Smith, B. T. Hosking. One Student Member Mr M. J. de Beer. Seven visitors. The Chairman reminded members of the intended visit to Barberton. Dr Stander, Director of the National Institute for Water Research, gave an interesting talk, illustrated with slides and a short film, on the conservation and reclamation of water in South Africa. After question time, Mr Hector, Witbank Town Engineer (visitor) thanked Dr Stander. The meeting closed at 7.10 p.m.

G. H. CLEVENGER, Colorado Springs, Colo.-Mr. Crowe's paper will be of great interest to cyanide operators, as it is a distinct new development in cyanidation. After reading the paper it occurred to me that some of us had done practically the same thing some time ago, but without design and unconsciously. I refer particularly to the operation of some of the earlier types of vacuum filter, used in connection with a dry vacuum pump and a receiver, which is somewhat similar equipment to that employed by Mr. Crowe. However, we did not appreciate the good effects we were getting from such of this solution as was precipitated, and it has remained for Mr. Crowe to bring distinctly to our attention the advantages of removing air from cyanide solutions before precipitation. Full credit is therefore due him for this very clever improvement in the cyanide process.

Jan 11, 1918

The greater part of this paper comprises the material used in a lecture delivered to the South Queensland Branch of the Australasian Institute of Mining and Metallurgy in September, 1949. It contains little in the way of original matter, its main purpose being to call attention to the need for research into the properties of Queensland coals and to indicate some of the lines such investigations might profitably follow.Since the lecture was given the Powell Duffryn (1949) 1 report, which has made an excellent start along these lines, has been printed. This report is, however, only a beginning, though a big one, and there is ample room for many years of work along similar lines.The paper is based largely on the work of de Jersey (1946, 1949)2,3,4,5 and Jones and de Jersey (1947)6, but these workers in turn owe a debt to the work of many British and American investigators, too many to enumerate. The subject is a very large one-to deal with it fully would require not a paper but a book; all the author can hope to do is to discuss very briefly some of the main lines of investigation and indicate some of their applications.The reason for selecting Queensland coals in particular is the widespread ignorance of the extent of the coal resources of that State and the almost complete ignorance, to within the last year, of the modern industrial purposes to...

Jan 1, 1950