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By Israel Liebman

The Bureau of Mines developed three types of passive water barriers for suppressing slow-moving coal dust explosions. One type is a modification of a conventional tub barrier and depends on the dynamic pressure generated ahead of an explosion to tilt the tub to release its water and suppress the explosion. The other two barriers operate in response to an increase in static pressure developed ahead of the explosion. Tests indicate the first barrier begins to release its water at air speeds as low as 50 ft/sec, and the second and third barriers will operate at a rise in static pressure as little as 0.5 psi. All three barriers were found to be effective in suppressing coal dust explosions propagating at speeds as low as 100 ft/sec. A plan is described for installing a water barrier in a working mine on a trial basis.

Jan 1, 1976

By Henry J. Kellner, Michael J. Brnich

This U.S. Bureau of Mines report addresses issues involved in using a limited number of training apparatus to give hands-on self-contained self-rescuer (SCSR) training to a succession of miners, and provides guidance regarding methods for minimizing the spread of infectious diseases. Procedures used for preventing the spread of infectious organisms in dentistry, cardiopulmonary resuscitation (CPR) training, and scuba training are examined. The sanitizing methods of three organizations that require individuals to insert the mouthpiece as part of the SCSR donning sequence are discussed. It was found that each of these organizations was able to render their mouthpiece assemblies microbe free simply and inexpensively.

Jan 1, 1989

By Norman Orr, J. W. Gregg, Jack Wahl

The Pembina Cardium pool is a low permeability, stratified, solution-gas drive reservoir. Water-flooding has proven to be an effective means of pressure maintenance for all areas of the pool in which an economic rate of water injection can be maintained. The majority of water injection wells in the pool are converted oil well~ with capacities greater than 100 millidarcy-feet. If the average injection rate per unit of capacity can be in-creased the lower capacity areas of the pool can be economically flooded. Theory, laboratory work, and two . early miscible-flooding projects with-in the pool suggested that average water injection rates for converted wells could be increased two to three-fold by the initial injection of natural gas liquids and natural gas. How-ever, these two early projects received volumes of natural gas liquid!:' and high-pressure natural gas which would be economically prohibitive for routine stimulation. Area D, one of the Five-

Jan 1, 1962

By Go-Gi Lee, Jae-Young Jung, Myung-Duk Seo, Hyun-Na Bae, Seon-Hyo Kim

"Bubbles form at the anode during the electrowinning of magnesium and cause hydrodynamic acceleration and electrical field disturbance. A three-dimensional computational model was developed to investigate the effects of the geometry of the electrochemical chamber and the size distribution of bubbles on the fluid flow in the pilot plant. The results are validated by measurements of the surface characteristics of molten salt and the bubbles formed. Fluid flow at the surface was recorded with a high speed camera, and the distribution of bubble size is determined by inspecting the video images frame by frame. The measured size distribution of the bubbles is entered into the computer simulation of a multi-phase flow. A sloped roof is installed above the electrodes, to enhance the flow of the molten salt, thus resulting in higher current efficiency, lower energy consumption, and higher quality of magnesium metal.IntroductionTitanium's excellent properties of low density, high specific strength, high temperature strength, and exceptional resistance to corrosion are highly beneficial to diverse applications including aerospace, automotive, construction, and medical implants. Although the Kroll process[l] and Hunter process have been used for the extraction of titanium in the 20th century, their complicated engineering stages and high production cost, have led to further research into new processes such as FCC Cambridge, Armstrong and TiRO. Despite these intense research efforts, no process has yet been developed that is more economical than the Kroll process, by which most of the global commercial titanium is still being produced."

Jan 1, 2011

By Vladimiros G. Papangelakis

During the past five years, chemical modelling work at the University of Toronto has elucidated the role of soluble magnesium on the autoclave acidity and has demonstrated why feeds rich in magnesium, and other divalent metals, require more than the stoichiometric requirements in acid to produce a leaching performance comparable to that of low magnesium feeds. This understanding has allowed the calculation of acid additions to the pressure acid leach (PAL) on a less empirical basis. Optimizing acid additions to the PAL confers savings in neutralization costs, ensures high productivity and minimises corrosion problems. Hence, our picture of the solution chemistry inside the autoclave during the PAL process has been substantially improved and is reviewed here. Experimental techniques based on solubility and direct acidity measurements that support the theoretical predictions are presented. Concepts of chemical modelling of electrolyte systems at high temperature and software issues are also discussed. Finally, a better understanding of the solution chemistry at temperature has led to better kinetics models because all metal dissolution and precipitation reactions are acid driven and controlled. . Therefore, reactor modelling efforts by our group are also presented and a reactor model with very good performance, as compared to pilot-plant data, is also made here. Finally, in spite of the above success in PAL solution chemistry and reactor modelling, significant challenges lie ahead in theoretical data gaps and instrumentation; these are also discussed in this paper. Keywords: Laterites, process modelling, pressure acid leach, solution chemistry, chemical modelling, reactor simulation

Jan 1, 2004

By J. P. Matoney

In recent years, the diminishing supply of natural gas has led energy suppliers and consumers to consider making synthetic natural gas from coal. A number of processes have been devised to produce gas from coal; many of these have been operated at the pilot stage and some have been operated commercially. Each process has specific coal feed stock requirements with respect to size consist and moisture content. The purpose of this presentation is to compare the estimated costs for coal handling, live storage, size reduction and drying facilities that would be required for delivery of coal feedstock to different gasification processes.

Jan 1, 1977

By Anne Kvithyld

Silicon solar cells, that convert the energy of sunlight into electric energy, are attractive sources of energy. In the production line wafers of solar cells are sliced from a multicrystaline ingot solidified unidirectionally. Recycling scrap from top and sides of such ingots is addressed. SiC and Si3N4 inclusions are a major problem. Scrap from Scan Wafer ASA is melted in a high vacuum furnace at around 1500ºC. The filters, from commercial producers, are C and SiC with 10, 20 and 30 ppi. Characterisation of inclusions before and after filtration, and in the filter itself, is performed by microscopy. Dissolution of silicon in acid and counting of the un-dissolved inclusions is also carried out. In the filter Si3N4 needles and SiC inclusions were identified. The amount of these inclusions in the filtered silicon is much less than in the input. In conclusion, filtration using SiC and C filters in vacuum system in argon atmosphere removes SiC and Si3N4 inclusions from solar cell scrap. Flow of metal through the filters is not a problem. These results are promising with scale-up to industrial application in mind.

Jan 1, 2006

By Sidney Katell

This Bureau of Mines study estimates capital investment, operating costs, and selling prices for three underground bituminous mines producing coal with annual production ranging from 1.03 to 3.09 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of November 12, 1973, under the Bituminous Wage Agreement of 1971, and costs for material and equipment are based on 1973 indexes. Initial capital investment ranges from $12,938,200 for the 1.03-million-ton-per-year (MJ.Vl tpy) mine to $31,435,500 for the 3.09 MM tpy mine. Total capital investment ranges from $21,607,200 to $51,982,000 for the same mines. Corresponding selling prices for the coal range from $9.11 to $8.06 per ton, assuming a 12-percent discounted cash flow rate of return after Federal income taxes.

Jan 1, 1974

By Qing-Xun Low

Ni current collector has excellent electronic conductivity and mechanica, properties. However, nicke, cannot be used in H2S-containing syngas SOFCs due to sulfur poisoning and coking. Copper coated nicke, is prepared by electrochemica, deposition. XRD, SEM, and EDX techniques are used to characterize the samples. After high temperature treatment in syngas containing, the coated samples exhibit high resistance of coke formation and sulfur corrosion compared to pure nickel. Therefore, copper coated nicke, is a promising anode current collector for H2S-containing syngas SOFCs.

Jan 1, 2010

By R. Edinger

Aerospace and space products depend, probably more than any other products in industry, on advanced materials. While there are many ways of producing aerospace parts, in many cases the process does not allow the design of the metallurgical properties according to the part or product requirements in accordance with its mechanical configuration. Key to the next level of innovative manufacturing is the capability to control the amount of energy applied to the process, as well as the addition of materials in form of vapor or solid particles such as powder in order to build up the metallurgical composition required. With the development of a high speed pulsed laser-electron beam source, the LASTRON(TM) technology, we deliver the basic requirement for a digital manufacturing process of aerospace and space products. This technology, combining Laser and electron beam, finds application in welding, drilling-machining, and is currently modified to allow digital coating (PEB-PVD) methods. In addition to the coating, a powder metallurgical process, called Rapid Manufacturing (RM), will allow the precision melting of parts based on CAD/CAM files. The RM process and the digital coating will allow the production of graded aerospace alloys in parts for jet engines and aero-structures.

Jan 1, 2006

By A Singh, C Da Corte

Banded Iron Formations or more commonly known as BIF are sedimentary rock formations with alternating silica-rich layers and iron-rich layers that are typically composed of iron oxides (hematite and magnetite), iron-rich carbonates, and/or iron-rich silicates. Considering the depletion of highgrade iron ore reserves in South Africa, there is a need to maximise resource utilisation through the exploitation of sterile resources in particular BIF material which makes up greater than 65 per cent of current reserves. BIF, like most resources, is non-renewable and the deposition of BIF is thought to have come about by the reaction of Fe2+ ions in the ocean water with dissolved oxygen billions of years ago. BIF ore derived from the Limpopo region in South Africa (SA) located in the Penge Iron Formation is according to Cairncross, Kramers and Villa (2018) equivalent to that contained within the Asbestos Hills Iron Formation of the Transvaal Supergroup in the Northern Cape, SA. Considering that these are one of the largest iron ore deposits in SA, the case study involved mineralogical characterisation followed by beneficiation of BIF from these two regions to ascertain the comparability. Coarse and fines gravity separation comprising of Heavy Liquid Separation/Dense Media Separation on the +1.18 mm size fraction and shaking table on the -1.18 mm size fraction was conducted to ascertain whether an on-grade product or blended feedstock could be produced. The Limpopo mixed and Northern Cape conglomerate BIF samples achieved similar overall responses due to the conglomerate sample containing 15.3 per cent additional -1.18 mm fines. A combined coarse and fines product grading at 60 per cent Fe could be achieved at a yield and recovery of 43.9– 53.0 per cent and 62.2–63.8 per cent respectively. Increasing the grade to 63 per cent Fe reduces the overall recovery by 13.3 per cent. At the higher target grade, the contaminant specifications could be achieved for both samples. The Northern Cape laminated BIF sample is the most promising of the three samples studied. At the two iron target grades overall yields and iron recoveries of 72.9–65.4 per cent and 85.2– 80.2 per cent was achieved. In both instances the silica grade exceeded the product specification, however if the silica content is the driver the target iron grade should increase to 63.32 per cent. This will result in a minimal decrease in recovery of 0.4 per cent. The promising results of this study indicate that coarse beneficiation of BIF material is possible. These ore types could be blended with superior grade products to improve overall yields and recoveries or sold directly at a 63 per cent Fe product grade whilst sacrificing 0.4–13.3 per cent recovery.

Nov 8, 2021

By H. B. FERNALD

THE interesting and carefully developed formula which Professor Bucky presents for answering the question of whether proposed new equipment will give a net return on investment equal to or greater than that on present equipment starts with an assumption that the management may make this relative return a determining factor in its decision whether or not the new equipment should be provided. I do not question that in some cases the management may take this position, but I would point out the error involved in so doing. The proper test is not a comparison of the return on new as compared with the return on old investment, but is rather a comparison of the return on a particular new investment as compared with the return which would be obtainable from some other new investment which now might be made. Then I would point out that I believe Professor Bucky is in error in using as a factor in his computations the item of unamortized cost of old investment. The financial advantage to be derived from a new investment does not depend on the extent to which we may in the past have written off the cost of old equipment, nor does it even depend upon what was the original cost of that old equipment. Even the salvage or resale value of the old equipment will only enter into the picture to the extent that the present salvage or resale value differs from the ultimate salvage or resale value otherwise to be obtained, after due allowance for the interest factor.

Jan 1, 1930

By Joseph E. Matta

The Bureau of Mines conducted a field study to investigate thin suppression of respirable dust by water sprays on a continuous-mining machine. Determining the importance of the top and bottom sprays for two types of spray nozzles was emphasized. Results showed, at a 90-pct confidence level, that (1) at least 70 pct of the dust was generated during the sump cut, even though nearly half of the coal was mined during the downshear operation, (2) the water sprays on the top of the boom had little effect in suppressing respirable dust, and (3) B.D. 5 spray nozzles mounted beneath the boom reduced dust at least 33 pet more than B.D. 5 sprays mounted on top of the boom. A single-cut technique was developed that gave good reproducibility for replicate cuts (coefficient of variation of 20 pct).

Jan 1, 1976

By H. R. Babitzke

The purpose of this Bureau of Mine- investigation was to develop columbium and tantalum alloys suitable or u at elevated temperatures. Columbium and tantalum were combined with tungsten, hafnium, zirconium, molybdenum, vanadium, and titanium, and the resulting alloys were evaluated with respect to workability, hardness, electrical resistivity, strength at elevated temperatures, oxidation resistance, and weldability. Cb-33Hf-10W-10Ti, Cb-20111-5Mo, and Cb-30Hf-5Mo exhibited superior high temperature properties. Cb-33Hf-10W-10Ti had tensile strength values of 44,300 psi at 1,200° C and 16,500 psi at 1,400° C, Cb-20Hf-5Mo had values of 35,700 and 20,700 psi, respectively. The corresponding values for Cb-30Hf-5Mo were 38,900 and 17,800 psi. These alloys are fabricable by conventional methods with excellent strength at temperatures up to and including 1,400° C. An oxidation rate of 7 to 21 mg/cm2/hr was observed up to 1,000° C.

Jan 1, 1967

By A M. Lechner, V Glenn, M Edraki, D R. Mulligan, C Unger

With more than 50 000 recorded abandoned mines in Australia, effective management strategies are needed to prioritise and manage health, safety, environmental and socio-economic risks and opportunities. This paper reviews international leading practices for abandoned mine management and identifies key issues that need to be addressed in the Australian context. As well as the academic literature, this review draws on a 2008 global legacy site survey and forum in 2008, a Churchill Fellowship study of abandoned mines and the recently released æStrategic Framework for Management of Abandoned Mines in the Minerals IndustryÆ (MCMPR/MCA, 2010).A conceptual model was developed to identify the relationship between key issues affecting the management of abandoned mines in Australia. The conceptual model is then used in the development of a maturity chart which draws on risk management principles to provide leading practice guidance for abandoned mine managers, jurisdictions and stakeholders. The maturity chart approach for risk management has been successfully used elsewhere to evaluate safety, environmental and socio-economic maturity.CITATION:Unger, C, Lechner, A M, Glenn, V, Edraki, M and Mulligan, D R, 2012. Mapping and prioritising rehabilitation of abandoned mines in Australia, in Proceedings Life-of-Mine 2012 , pp 259-266 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By AIME AIME

SECOND only to the February Annual Meeting of the Institute are the Regional and Divisional meetings held in the fall of each year. Six such gatherings are scheduled in the next the months, with something likely to interest every member of the Institute. A brief résumé of the programs follows. Regional Meeting Vancouver T HE regional meeting of the Institute will be held at Vancouver, Sept. 13 to 20, in conjunction with the annual western meeting of the Canadian Institute of Mining and Metallurgy. The pro gram appeared on page 350 of MINING AND METALLURGY for July and-proof of careful preparation-a month later re- quires no correction and little elaboration. On the technical side there are few changes. A new item on the Wednesday morning program is the paper, "Investigation of Residential-type Stokers," by H. F. Yancey, supervising engineer, Northwest Experiment Station. U. S. Bureau of Mines, Seattle. As to entertainment the meeting is taking on some most pleasurable aspects. Two notable excursions have been arranged.

Jan 1, 1937

By Robert B. Hoekzema

This Bureau of Mines report describes the history, characteristics, distribution, and mineral development potential of 21 lode gold deposits in or near the Chugach National Forest (CNF), AK. It includes findings from a 4-yr (1979 to 1982) mineral evaluation of the CNF conducted by the Bureau and the U.S. Geological Survey (USGS). This evaluation, undertaken to provide the U.S. Forest Service with mineral resource data for use in making decisions on land use, included site-specific mapping and sampling of more than 200-lode gold deposits. The data presented here were compiled from the findings of this 4-yr evaluation and from existing literature. Fourteen of the 21 lode gold deposits described in this report contain a combined identified resource of 117,750 short tons (st) averaging 0.55 oz/st Au and 0.2 oz/st Ag. Two mineralized felsic dikes in the Summit Lake-Palmer Creek area contain a combined identified resource of 18 million st grading 0.02 oz/st Au and 0.16 oz/st Ag. Identified resources were not determined for the remaining five deposits because of a lack of information.

Jan 1, 1987

By T. B. Linde

The Morenci In-pit Crusher and Conveyor System has been designed with safe production and cost savings in mind. Large open pit mines around the world have been installing semi-mobile crushers and linking them with a pit conveyor system to lower unit cost. At Morenci two 60/89 in. gyratory crushers are incorporated into the semi-mobile crushing plants. The ore is reduced to -8 in. and transported out of the mine on a 60 in. steel cable belt. This paper includes an overview of the Morenci In-pit Crusher and Conveyor System from the drawing board to open pit installation and finally a discussion on operating and repair considerations.

Jan 1, 1990

By J. Chipman, N. J. Grant, B. M. Shields

The vacuum tin-fusion method of analysis for hydrogen, developed by Carney, Chipman, and Grant, has been modified to permit the analysis of the evolved gases for hydrogen by means of a thermal conductivity cell. A properly prepared sample can be analyzed in 10 min with a probable error of ±0.12 ppm. A study of various methods for storage of hydrogen samples shows that samples can be safely held in a dry ice-acetone bath as long as six days. Storage in liquid nitrogen is necessary for samples to be held one week or more. HE vacuum tin-fusion method, as developed by I- Carney, Chipman and Grant,' is the only analytical procedure which has shown promise of being fast enough for use in the control of hydrogen during steelmaking. It was felt that further simplification and faster speed of operation could be effected by the use of thermal conductivity measurements for analysis of the gases evolved in the tin-fusion method. The application of conductivity measurements to the tin-fusion method is possible because: 1—the evolved gas is essentially a mixture of hydrogen, nitrogen and carbon monoxide with a hydrogen content usually over 50 pct, 2—the evolved gas is collected at a relatively low pressure, and 3— the thermal conductivities of CO and N2 are practically identical while that of hydrogen is very much greater. The major part of this research program was devoted to the construction and calibration of a vacuum tin-fusion apparatus which analyzes the evolved gases for hydrogen by means of a thermal conductivity cell. The second phase of the problem was associated with the development of a procedure for storage of samples prior to analysis. With the rapid quenching method for hydrogen sampling,' which seems to be the most practical for steel mill use, it is necessary that the samples be stored safely during the interval between sampling and analysis if the hydrogen content of the molten metal is to be maintained in the supersaturated solid samples. The thermal conductivity bridge has been used for a number of years in the analysis of certain gas mixtures. An elementary discussion of the theory and practice of gas analysis by thermal conductivity measurements is given by Minter.3 A more comprehensive discussion of the theory and of the various measuring circuits is presented by Daynes.' A complete knowledge of the theory and properties of the thermal conductivity of gases and gaseous mixtures can be gained by a study of the standard textbooks on the kinetic theory of gases."' The existing data on the thermal conductivity of single gases are reviewed by Hawkins: that for a number of binary gas mixtures by Daynes' and Lindsay." The thermal conductivity method may be applied to the determination of the composition of a binary mixture if: 1—the thermal conductivity of the mixture varies monotonically with composition, and 2— the two gases have measurably different thermal conductivities. The greater the difference between the two gases, the greater the sensitivity of the method.10 he method is applicable to the analysis of multicomponent mixtures when all of the gases in the mixture except one have nearly the same thermal conductivity. Fortunately, the mixture of hydrogen, nitrogen, and carbon monoxide evolved by the tin-fusion analysis' falls in this latter classification. The thermal conductivities of nitrogen and carbon monoxide are practically equal; and the thermal conductivity of hydrogen is approximately seven times that of the other two. Therefore, the thermal conductivity of a gaseous mixture of hydrogen, nitrogen, and carbon monoxide at known temperature and pressure can be related directly to the percentage of hydrogen in the mixture by suitable calibration. Usually the thermal conductivity of a mixture of gases is measured at atmospheric pressure where the thermal conductivity is independent of pressure over a wide pressure range. At very low pressures (below 1 mm Hg), the thermal conductivity of gases varies with the pressure. This phenomenon has been utilized in the Pirani vacuum gage for the measurement of pressures in the range of 10" to 10-0 mm of mercury.= Very little has been published concerning the variation of thermal conductivity with pressure at intermediate pressures between 1 mm Hg and 1 atm. However, preliminary measurements indicated that the thermal conductivities did vary with pressure over the range of pressures (up to 10 mm Hg) at which gases are delivered from the vacuum pump. Therefore, the calibration of the thermal conductivity cell had to be planned to include the effects of both gas composition and pressure. Such a calibration chart is shown in Fig. 4. Most industrial applications of the thermal conductivity method of gas analysis have used a compensated Wheatstone bridge circuit containing two

Jan 1, 1954

By R. O. Loutfy, J. C. Withers

"Titanium powder is produced from a small fraction of sieved sponge, HDH of sponge or gas blown from a melt produced billet. Ore from foreign sources is chlorinated in a very high temperature fluid bed to make TiCl4, then vacuum distilled purified and then reduced to sponge by Kroll processing. Domestic ores of ilmenite or perovskite can be carbothermically reduced to Ti2OC which can be chlorinated at low temperatures of 250–400°C to produce TiCl4 which can be electrolyzed in a fused salt to Ti powder, or the Ti2OC used as an anode in electrolysis to produce Ti powder. The electrolysis process can be operated continuously to produce Ti powder at a lower cost than Kroll processed sponge including produce control size powder. Electrolysis processing was scaled up and operated at the commercial demonstration stage on a continued basis that verifies the potential of a low cost process to produce Ti powder.INTRODUCTIONTitanium and alloys of titanium powder have been elevated to strategic status resulting from a focus of producing meltless titanium components as well as a feed for additive manufacturing processing. However, the high cost of titanium powder has limited wide scale implementation of using titanium powder as a feed to any process to produce titanium components. Titanium powder free of alloying is available as sponge fines from the Kroll process as illustrated in Figure 1. Titanium alloy powder is much more expensive, also illustrated in Figure 1 produced from an alloy ingot or mil product as the feed and then transformed into powder by one of several melt form processes which accounts for the high cost of titanium alloy powder at approximately $60–150/lb. Ton lots of titanium alloy powder (i.e. Ti-6Al-4V) from one source is quoted at $120/lb. in the U.S. It appears that alloy powder production cost by current processing is not sensitive to volume."

Jan 1, 2016