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By B. Rai

Aluminum is produced by the Hall-Héroult process, which involves passing a current through a molten mixture of alumina dissolved in cryolite (Na3AlF6) to reduce the alumina to aluminum. This process occurs in an electrolytic cell comprising a steel shell lined with a carbon cathode and refractory bricks. After a certain period of operation, the carbon cathode deteriorates and is removed from the cell along with the refractory bricks. These removed materials are referred to as spent pot lining or ?SPL?. Typically, 30 Kg of SPL waste is generated for every ton of Aluminum produced. Globally aluminum smelters produce more than 500,000 tons of SPL each year. Even though SPL has a high fuel value (8000 to 9000 BTU/lb) and contains valuable metals, it is classified as a hazardous material due to its cyanide content and leachable fluorides. Various disposal/recycle techniques have been developed over the years for SPL but none of them is satisfactory. Thus, large quantities of SPL are still being dumped in landfills. In some countries, even the land filling of SPL is not permitted. The safe disposal of SPL thus remains a challenging problem to the aluminum industry and the search continues to find methods of converting SPL into a non-hazardous waste and/or recovering the valuable materials contained in the SPL. We have developed a process to produce hydraulic setting cements (eco-cement) containing a novel fluoride rich cementitious phase, from SPL by an energy efficient, low temperature clinkering route. A raw mix blend of SPL, lime/limestone, calcium sulfate and tailings sands based on a set of design criteria developed by us, is clinkered in a two stage process; 2 hours soak at 800 °C followed by clinkering at 1000 °C for another 2 hours, to produce a soft clinker. The SPL eco-cement is made by grinding the clinker to a fineness of 5000 cm2/g Blaine with 1% by weight borax as a set retarder. A good quality cement having as high as 20 % by weight of SPL in the raw mix (28 % by weight in the cement clinker) is thus produced. The physical properties of the SPL cements are found to be comparable to the Indian standard (IS) specifications for Ordinary Portland Cements (OPC). We have produced the cement in a few Kg batches and tested the reproducibility of results from batch to batch for further scale up. Once commercialized, this process has a potential of converting SPL into value-added cement products. Keywords: cement, spent pot lining, clinkering, fluoride, aluminum, ordinary portland cements

Sep 1, 2012

By R. L. Grayson

Productivity achievements in underground coal mining over the past ten years highlight the improvement of management practices as well as the adoption of new technology. Research findings and results from operational studies characterize the aspects of good management that translate into high productivity. In concert with these findings, the Mine Management Support System (MMSS) is being developed, under co-sponsorship of the U.S. Bureau of Mines and the West Virginia University Energy and Water Research Center, as a knowledge-based system to enhance more efficient management of underground coal mines. Concentrating on capturing the intricate knowledge needed to manage a mine effectively, MMSS will encompass information and rules on work scheduling, desired work practices, regulations impinging on operations and planning, responses to operating problems, and the labor-management work agreement.

Jan 1, 1990

Cyril w. Knight, Toronto, Ont., Canada (communication to the Secretary*).—Mr. Hore's paper presents an interesting summary of our knowledge of this important mineral field ; and is therefore acceptable as giving information which our Transactions did not already contain, although it presents little or nothing not made known by other writers before 1906, when Mr. Hore began work in the field as a student assistant. Contributions of this kind, however, should be made completely valuable by such references to previous work as will enable the reader to follow to their original sources the theories or conelusions stated by the author. It is quite natural, and even excusable, that a new observer should find novelty in his on observations—especially if he is not acquainted with the work of predecessors in the same field. Moreover, the independent repetition of an observation or conclusion has a distinct value as a confirmation, though it may have none as a discovery. But the publication of it, without reference to its predecessors, may place the author in an unfavorable light as either ignorant of the history of his subject, or willing to claim credit to which he is not entitled. Of the latter fault, I do not accuse Mr. Hore ; but I cannot wholly acquit him of the former. Without disparaging his intelligent work, I must point out that his paper, as it stands, might easily give the impression that he claims originality for many statements which are by no means new, and that he emphasizes unduly his own publications. Thus, his remark (p. 481) "I have described the silver-fields in a general way in my paper " (not yet published), should have been accompanied with reference to some of the numerous papers, already published, which describe these fields. Again, on p. 486, he refers to four papers of his own on the Porcupine gold-area, but neither in the text nor in the appended

Jan 1, 1912

By Christian Ludwig, Virginie Silberstein, Rizlan Bernier-Latmani, Simona Regenspurg

"Residues from waste incineration (bottom ashes) form large amounts of heavy metal-rich waste. Theoretically, heating and the addition of chloride to the ashes could remove these metals by formation of volatile metal chlorides. The remaining heavy metal-poor ashes could be used, for example, as cement additives. In the proposed process of our study we used bypass dust from the cement industry as chloride additives to the bottom ashes. We aim to determine experimentally the optimal conditions to remove heavy metals from ashes and to simulate this process by thermo- chemical modeling. In our experiment we investigate heavy metal flows by heating of differently composed mixtures of bottoms ash and bypass dust in dependence of different furnace temperatures (500-1200 °C). Furthermore, we investigate the reactivity (leaching characteristic) of the resulting product in order to predict if secondary residues can be landfilled in agreement to Swiss regulations for inert materials.IntroductionThe incineration of garbage is generally considered as the most environmentally friendly method for the reduction of municipal solid waste. This is because, compared to traditional storage of waste on landfills, incineration produces less greenhouse gases and destroys toxic organic compounds. The released exothermic energy can be recuperated and the residues from the combustion chamber (bottom ash) are strongly reduced in volume. However, they still form about 600 kt of waste per year in Switzerland, which needs to be landfilled. However, these residues could be potentially used as construction materials after mechanically recovering ferrous and non-ferrous metals. However, the resulting ashes (discharged dry or wet) still contain increased amount of heavy metals (exceeding state regulation) requiring them to be finally deposed on a hazardous waste site. A thermal treatment of these ashes could enable both, to separate and recuperate the remaining heavy metals and an inorganic heavy-metal poor material. The evaporation of metals depends on temperature and can be lowered by addition of chlorides, which would lower the boiling point of most metals by formation of metal chlorides (table 1)."

Jan 1, 2008

By E. M. Norris

During the winter and spring of 1917, an unprecedented number of underground fires occurred in the Butte district. With one exception, these fires were caused by the failure of electrical equipment, and called attention to the increased fire hazard in underground mining operations occasioned by the extensive use of electricity. Five local conditions that contributed toward a heavy fire risk were: (1) The heavy continuous timbering necessary for mine supports; (2) the strong ventilating pressures in the shafts and main airways; (3) the subsidence and faulting movements in the country rock, which ruptured cables and displaced trolley and lighting wires; (4) the strongly acid mine waters, which quickly developed any weak points in the electrical insulation; (5) oxidation in old stopes containing large amounts of timber. In the summer of 1917, a comprehensive plan of fire prevention was begun by the Anaconda Copper Mining Co., which involved a thorough and intensive development of the preventive measures then in use. These were as follows: Fireproofing, remodeling and strengthening electrical insulations, extension of underground water system, control of ' ventilation, maintaining efficiency of fire-fighting crews, and reorganization of fire patrol. In considering the problems of fireproofing, it was immediately apparent that some method of applying a durable coat of fireproof material to the mine timbers was needed. The first experiments were made with a plaster composed of one part cement, one-half part fireclay, and three parts sand. This was applied by hand to a thickness of 1 in. (2.5 cm.) over a reenforcement of herringbone metal lath. It made a very satisfactory covering for fan stations, but was too soft and friable for traveling ways, where it was subject to abrasion. The cement gun was tried next with a three to one mixture of sand and cement. A 1/2-in. coating of gunite applied over poultry netting or metal-lath reenforcement proved

Jan 1, 1923

By A. Fouchee, N. Naudé, K. Schommarz

"This article presents laboratory test work conducted on an African haematite ore to determine the influence of the flotation pulp pH on the final iron grade and recovery. Results show that a combination of an isodecyl ether propylene amine/amino acetate and 1,3-propanediamine, N-(3-(C10-C16-alkyloxy)propyl)-derivatives collector is suitable for separating haematite from quartz. Higher iron grades were obtained at pH levels between neutral and pH 9. This underlines the importance of the surface charge effect of the ore on its flotation characteristics. The results serve as good baseline conditions for further optimization. IntroductionBeneficiation of iron ore by flotation is widely used in Brazil, India and China. In Africa, however, this practice is not yet commercially developed.The aim of this test work is to serve as a starting point by establishing suitable pH conditions for the development of a practically implementable reagent suite, which will then be included in a larger beneficiation circuit for producing high-grade iron ore sinter feed.In the literature, African iron ore types are graded as low-grade (60.0–62.9% Fe; 8.6– 12.5% SiO2 and insolubles), high-grade (66.0– 69.9% Fe; 0.8–4.5% SiO2 and insolubles), and meduim-grade as the remaining portion (Astrup et al., 1998). The low-grade ore used in this work contains less than 60% Fe.For Brazilian ores consisting of a combination of haematite and quartz, it is common to use corn starch as a depressant and ether amine blends as collectors with additional frothing characteristic (Araujo et al., 2005). Work by Turrer and Peres (2010) shows the possibility of using other depressants successfully as well.The main mechanism of the reverse flotation of quartz from iron ore is based on the electrostatic theory of flotation. This is due to the strong pH dependence of the zeta potential of the mineral edge planes on silicate particles (Fuerstenau and Pradip. 2005)."

Jan 1, 2016

By G. H. Faye

The prospect of obtaining high-grade concentrates from Canadian pyrochlore ores is rather unlikely, and experimental beneficiation pro-cesses ?appear to have yielded products in the range of 3 to 20 per cent N'b205? A possible solution of the problem is to find an economical chemical method for recovering high-purity Nb2?05 from such concentrates. A technically feasible but economically unproved process is outlined in this paper, in which the concentrate is decomposed by an acid attack and the oxides of niobium and tantalum are isolated and then separated by liquid-liquid extraction. The solution of the ore is adjusted to 7 M HF-5 M HNO3 and the niobium and tantalum are extracted from this solution with methyl isobutyl ketone. The mixed oxides of niobium and tantalum are recovered from the oxdanic phase and dissolved in 0.5 M HF-1.0 M HNO3. Tantalum is extracted preferentially from this solution with methyl isobutyl ketone, leaving niobium in the aqueous phase. By the use of this process it is possible to produce niobium pentoxide and tantalum pentoxi.de in 99.5 per cent purity with a recovery of approximately 95 'per cent, under lab-oratory conditions.

Jan 1, 1957

By E. M. Norris

During the winter and spring of 1917, an unprecedented number of underground fires occurred in the Butte district. With one exception, these fires were caused by the failure of electrical equipment, and called attention to the increased fire hazard in underground mining operations occasioned by the extensive use of electricity. Five local conditions that contributed toward a heavy fire risk were: (1) The heavy continuous timbering necessary for mine supports; (2) the strong ventilating pressures in the shafts and main airways; (3) the subsidence and faulting movements in the country rock, which ruptured cables and displaced trolley and lighting wires; (4) the strongly acid mine waters, which quickly developed any weak points in the electrical insulation; (5) oxidation in old stopes containing large amounts of timber. In the summer of 1917, a comprehensive plan of fire prevention was begun by the Anaconda Copper Mining Co., which involved a thorough and intensive development of the preventive measures then in use. These were as follows: Fireproofing, remodeling and strengthening electrical insulations, extension of underground water system, control of ' ventilation, maintaining efficiency of fire-fighting crews, and reorganization of fire patrol. In considering the problems of fireproofing, it was immediately apparent that some method of applying a durable coat of fireproof material to the mine timbers was needed. The first experiments were made with a plaster composed of one part cement, one-half part fireclay, and three parts sand. This was applied by hand to a thickness of 1 in. (2.5 cm.) over a reenforcement of herringbone metal lath. It made a very satisfactory covering for fan stations, but was too soft and friable for traveling ways, where it was subject to abrasion. The cement gun was tried next with a three to one mixture of sand and cement. A 1/2-in. coating of gunite applied over poultry netting or metal-lath reenforcement proved

Jan 1, 1923

By Venkata S. Vutukuri

Assuming a number of discrete leakage paths and treating the airflow through leaky duct line as a series-parallel combination of airflows along the duct and through leakage paths, exact solutions for auxiliary ventilation problems can be obtained. A computer program "SEGMENT'' has been written to solve problems using this method. However, most of the investigators have treated the duct lines with a uniformly distributed leakage and many have derived formulas assuming various boundary conditions and levels of simplification for the design of a simple auxiliary ventilation system An appraisal of accuracy of the various formulas has been conducted using the results from the program "SEGMENT' as benchmark and the formulas which give accurate results have been identified. The ranges of application for all the formulas have also been determined for 5 %error.

Jan 1, 1993

By M. C. Pietrobon

"A common problem in assessing the applicability of laboratory flotation data is determining how closely conditions during laboratory testing of the ore matches those that occur in a plant. Typical laboratory based investigations do not consider factors such as water quality, pulp temperature and the pulp chemical environment during both grinding and conditioning on laboratory flotation performance. Disregarding these important factors may seriously compromise the validity of conclusions based solely on laboratory experimental results. Furthermore, considering these factors during the flowsheet design stage in the development of new ore resources may reduce financial risk associated with building a new plant. A methodology is described here which embraces these factors in an attempt to bridge the gap between laboratory and plant. The methodology should be considered a vital first step in all laboratory based experimental programs and has implications for fundamental studies on the flotation behaviour of single minerals. This methodology increases the confidence with which findings of laboratory based studies can be transferred to the plant and highlights the effect of variables which may be accessible to manipulation in the plant.Pulp chemical parameters, such as pulp dissolved oxygen demand, pH, Eh, mineral oxidation and solution composition were manipulated in the laboratory by adjusting the duration of gas purging after grinding, the process water input and pulp temperature. A key finding was that matching of the laboratory pulp chemistry to the plant pulp chemistry was dependent upon oxidation after grinding. In turn, mineral oxidation was dependent upon the pH in grinding, water composition and the duration of oxygen purging after grinding. The methodology closely matched the dissolved oxygen demand and surface chemistry of laboratory and plant pulps."

Jan 1, 2002

By Robert B. Hopler

The hazards which naturally prevail in underground coal mines, always severe and unpredictable due to the loosely-consolidated strata in which coal is frequently found, are increased by the commonly-occurring combination of coal dust, methane, and explosives. It was recognized by the mid-nineteenth century that coal dust was the basic factor contributing to disastrous explosions killing hundreds of miners, and that the ignition of methane gas was often the source of the coal dust explosions. It was apparent that preventing the ignition of methane was a critical part of avoiding these disasters, and it was also apparent that one cause of such ignitions was the firing of explosives. In addition, it was found that dust explosions were often initiated by blown-out shots of explosives in the absence of methane.

Jan 1, 1996

By C D. McCullough, M Gerner

Rarely do opportunities arise allowing closure of a mine site to be planned as a key beneficial land use asset within a new urban growth area; particularly so well prior to cessation of mining.Pit lakes are common mine closure legacies for many open cut mines and may form in open cut mine voids extending below the water table upon closure. Mine closure guidelines increasingly require post-mining land uses of equivalent capacity to premining conditions and that minimise long-term post-mining liabilities and maximise benefits to stakeholders and the environment. However, risks presented by pit lakes are regularly neglected in closure planning or are not able to be addressed to allow beneficial end use of the lake or surrounding land.This paper describes strategic planning initiated by quarry owners ten years before mining ceases. In liaison with the planning agencies, the planned closure of a large 100-year-old limestone quarry pit will form a lake on mine completion, with a well-considered beneficial end use in an urban setting in mind. The quarry pit and adjoining land at Batesford South about the edge of the City of Greater Geelong, Victoria, Australia. Geelong is experiencing growth pressures that necessitate development of a new growth area from about 2025.A multidisciplinary expert team assessed the constraints, opportunities and feasibility of rehabilitating the quarry and pit lake and developing the surrounding land as Geelong’s next urban growth area.The concept is exciting and demonstrates that a former mine site could become a valued home to about 40 000–45 000 people. About 30 per cent of the land will also be developed as an ecological riverine corridor including the pit lake that will become a regionally iconic lake as the centrepiece of an urban development.Our paper outlines technical challenges and how these can be met to achieve closure and beneficial use that meets the social, economic and environmental expectations of contemporary urban planning.CITATION:Gerner, M and McCullough, C?D, 2014. Planning for the future – development of beneficial end use from a quarry pit lake, Victoria, Australia, in Proceedings Life-of-Mine 2014 , pp 99–112 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Peter N. Gabby

A mineral purvey of 40,000 acres of the 42,213-acre Little Humboldt River Wilderness Study Area was conducted by the U.S. Bureau of Mines in 1985 at the request of the U.S. Bureau of Land Management. There are no identified mineral resources but anomalous gold, silver, mercury, and arsenic concentrations were found. The study area is located in Elko County, NV, in the Owyhee Upland geomorphic subprovince. It is underlain by mid- to late-Miocene-age rhyolite, basalt, tuff, vitric ash, and tuffaceous siltstone. On the south side and partly within the study area, a mining company recently (January 1986) located 125 contiguous claims over an area of hydrothermally-altered volcanic rocks that have anomalous surface concentrations of gold, mercury, arsenic, and silver. Anomalous gold-silver concentrations in altered rocks were encountered at several other widely scattered localities in the study area. These elevated metal concentrations and associated hydrothermal alteration indicate gold resources may be present in the study area. A 20-ft-thick bed of diatomaceous earth, which contains 60 to 85 percent diatoms, crops out 0.3 mi north of the study area. Elsewhere, three samples of altered volcanic tuff taken within the study area contain from 46 to 70 percent zeolite (clinoptilolite). The diatomaceous earth and zeolite sampled are not of sufficient quality to compete with materials presently being marketed. There has been no mineral production from the study area, but a caved adit, about 25 ft long, and six prospect pits were found.

Jan 1, 1987

By William Y. Mo

The OPEC oil embargo and the subsequent higher prices for oil have drawn public attention to the critical problems associated with security of supply of oil and other key industrial materials, especially nonfuel minerals. This concern has stimulated the interest of decisionmakers in analyzing policy options to cope with the emergency situations resulting from a sudden foreign- induced supply interruption or a cartel price increase. Several policy options are available to counteract foreign-initiated embargoes or cartel price actions. The type of response will differ depending on the commodity action intiated. A mathematical model that measures the impact of foreign-induced commodity actions on the domestic economy is formulated. The paper also presents a computer method that can be used to determine the optimum policy response to counteract such actions.

Jan 1, 1977

By C. J. R. Braithwaite, Giancarlo Rizzi

"Abstract-The Navan zinc-lead ore deposit (70 million tonnes) is hosted principally (97%) by the Meath Formation (Lower Carboniferous, Courceyan, Navan Group), comprising a lower, mainly carbonate mudstone unit, the Stackallan Member, and an upper grainstone-dominated unit. The Stackallan Member, about 60 m thick, comprises about 35 peritidal cycles including an oolitic grainstone interval. Grainstones forming the upper part of the formation, about 150 m thick, comprise at least six shallowing-upward ramp cycles. Emergence horizons are indicated by subaerial dissolution surfaces, in situ breccias, and a single palaeosol.Most dolomitization at Navan is confined to the Meath Formation. The linear dolomite body, trending NE-SW, has a flattened, laterally limited, tabular geometry in cross-section, suggesting that dolomitizing fluids initially rose vertically, cross-cutting stratigraphic and sedimentological boundaries, although fluid flow was subsequently controlled by these features. Three stages of dolomitization are indicated by textural relationships, cathodoluminescence (CL), oxygen isotopes, and fluid inclusion data. Stage 1 crystals, with generally dully luminescing cores and up to six overlying subsidiary zones, are the main replacive phase. Crystal surfaces are commonly corroded and overlain by bright stage 2 rhombs (which also form new nuclei lining molds and fractures). Three subsets of zones are present in stage 2 crystals: bright, non-luminescent, and dull; these are locally separated by additional corrosion surfaces. Stage 3 comprises relatively large baroque crystals, generally dully luminescent but with up to seven sub-zones. Isotopic and fluid inclusion data suggest growth of successive stages from waters which became progressively hotter (60°-160°C).The distribution of the ores follows the dolomite trend. Ores were precipitated between Stages 1 and 2 of dolomite growth, following Stage 2, and also during the nucleation and growth of Stage 3 crystals. Dolomitization and mineralization appear to have been temporally and genetically related. The cyclic sedimentation of the host rocks, which accentuates lithological and petrographical contrasts between depositional units, controlled dolomitization. The relationship between dolomitization and mineralization, which is closely associated with faults, provides powerful exploration criteria. The recognition of these features in limestones elsewhere in the Irish ore field may point toward unrecognized zinc-lead prospects."

Jan 1, 1997

By Jerry E. Olson

In 1988, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied additional areas, encompassing 11,303 acres, on the east and west sides of the 20,727-acre Badlands study area (Olson, 1987) in order to evaluate their identified mineral resources. The Badlands study area additions are located in Crook and Deschutes Counties, OR, about 10 and 18 miles east of Bend, OR. No mineral resources were identified. The additional areas studied are underlain by Tertiary-and Quaternary-age basalt flows which are largely covered by a veneer of sand and silt. No mines, prospects, mining claims or mineralized areas occur within or near the Badlands study area additions. Slab lava of marketable grade and quantity was not found in either area. None of the study area is of current interest for geothermal resources, but the eastern study area addition has been leased (1984) for oil and gas.

Jan 1, 1989

By Kenneth L. Cashdollar

While underground coal technology has progressed over time, regulations on coal dust have not kept up ? the most recent rules are more than 80 years old. The National Institute for Occupational Safety and Health and the Mine Safety and Health Administration conducted a joint survey recently on coal particle ranges as measured in US coal mine samples. In underground coal mines, dust explosions are prevented by the addition of enough rock dust (usually limestone) to make the total dust mixture inert. The rock dust acts as a heat sink for the dispersed dust mixture by reducing the temperature below the value needed to propagate an explosion. Federal regulations require 65% in combustible content in intake airways and 80% incombustible content in return airways, where the coal dust is assumed to be finer in size. The regulations also require an additional 1% incombustible for each 0.1% methane in the ventilating air in intakes and 0.4% additional incombustible for each 0.1% methane in returns.

Jan 1, 2008

EUGENE WESLEY SHAW,* Washington, D. C. (written discussion ?).-Studies of the probable future production of oil wells and fields-particularly those in the nature of the recent work by Lewis and Beal, having the object of increasing the percentage of recovery-rank, in both practical and theoretic value, very high, if indeed they do not outrank all other petroleum investigations except structural surveys. Even such surveys, although saving untold millions that might have been spent in prospecting unpromising territory, may have less ultimate value than generally supposed, for it may perhaps be argued that much if not most of the condemned territory will sooner or later be tested-some is already productive-and the most that can be rightly claimed is the recovery of cream first; also that the consumption of the richest portions first cannot be extenuated, as it might with some resources, on the ground that if the best is not taken now it will deteriorate.

Jan 5, 1918

By G. W. P. Rengstorff, L. E. Olds

High purity molybdenum ingots containing controlled amounts of a single impurity element (oxygen, nitrogen, or carbon) were prepared. These ingots were tested for ductility by bending test specimens at various temperatures. The relationship between the plastic behavior of the ingots and their chemical composition has been determined. MANY proposed applications for molybdenum require ductility at or near room temperature. At the present time, it is possible to obtain wrought molybdenum with considerable ductility only if special fabrication techniques are used to control the grain structure. Starting with are-cast or powder metallurgy ingots, the usual methods for obtaining ductility rely on fabrication procedures that result in fibered microstructures in the finished product. Recently, it has been found that the ductility of either powder metallurgy or are-cast molybdenum can be improved by uniform recrystallization of the metal to a very fine equiaxed grain structure.' The need for a fibered or a fine grained structure may limit the practical usefulness of molybdenum. For example, welding. which may be used in fabricating the metal, generally produces coarse grained structures that lead to brittleness. This applies, certainly, to currently available commercial molybdenum. Although commercial molybdenum is brittle when the grains are coarse, it has been shown experimentally that fine grained structures are not always essential for ductility. For instance, as-cast molybdenum with a coarse columnar grain structure is ductile if it is sufficiently pure.' Because high purity cast molybdenum has good ductility even when coarse grained, it is probable that the brittleness in coarse grained commercial molybdenum is caused by the impurity content of the metal. Although the general effects of impurities on the cold ductility of molybdenum have been known in a qualitative manner for some time, no quantitative evaluation of these effects has been available. The present investigation was made in order to determine more accurately the effects of oxygen, nitrogen, and carbon on the cold ductility of cast molybdenum. Oxygen has long been known to be detrimental to ductility, although the minimum amount which will embrittle molybdenum has been open to speculation. Parke and Ham" showed that ingots with oxygen contents above 0.003 pct could not be forged. Maringer and Schwope have described the embrittle-ment of molybdenum wire by oxygen. A discussion on the effects of heat treatment on the distribution of oxygen in molybdenum has been given by Perry, Spacil, and Wulff." Although nitrogen would also be expected to have harmful effects on ductility, no extensive work has been done previously to determine whether this is so. However, Tury and Krausz" found that wires presumably with less than 0.007 pct N were brittle. Carbon is added to commercial cast molybdenum for deoxidation. Parke and Ham" have shown that molybdenum containing as much as 0.06 pct C could be forged if the oxygen was kept below 0.003 pct. Also, Bruckart and others' found that the room temperature ductility of sintered molybdenum improved with carbon contents up to 0.84 pct. However, Rengstorff and Fischer' found that residual carbide particles in cast molybdenum apparently had an unfavorable effect on room temperature ductility.

Jan 1, 1957

By George H. Schnakenberg, Aleksandar D. Bugarski

This report reviews the performance and applicability of technology for the control of emissions from diesel-powered equipment used in underground coal and metal/nonmetal mines. The methods discussed include Mine Safety and Health Administration-approved low-emission engines, engine derating, fuels, fuel additives, diesel oxidation catalysts, and diesel particulate filters. The potential of each of these technologies is examined individually and in combination. The performance estimates are derived from the published literature and presented in narrative and Tabular form. The purpose of this report is to help the mining industry select the most appropriate method to reduce underground exposures of miners to diesel exhaust in the context of the recently developed diesel regulations. It is important to note that the control technologies discussed in this report have received limited evaluation in underground mines. Additional research is ongoing, and some engineering design changes may need to be implemented before all of these diesel emission control technologies can be safely and successfully used in underground mines.

Jan 1, 2002