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By K. Biswas

For the pillars, which have been standing long after mining, the stability depends much on the weathering action in the presence of mine moisture. From the field observations, it has been found that this weathering action becomes critical in terms of pillar stability if the coal seam contains partings or binders in it. The weathering action degrades both the partings and coal in terms of their load bearing capacity as the mine moisture penetrates into them. This paper investigates the effect of weathering action on coal and partings in the laboratory. In the field, the strength profile in the coal and the partings and the effect of time (in terms of the pillar age) on them have been studied by using borehole penetrometer. In this paper, an attempt has also been made to establish formulae for time dependent strength of coal and partings.

Jan 1, 1997

By L. W. Vollmer

Introduction During the past three years at least fifty strings of 9% nickel steel tubing have exhibited excellent resistance .to the variably severe corrosive conditions typical of many of the sweet condensate wells in Mississippi, Louisiana, and Texas. This experience, and the characteristically outstanding performance of other ?nickel alloy steels under hydrogen sulphide corrosive conditions, dictated the selection of 9% nickel steel tubing for the second well drilled in the sour condensate Pincher Creek field of southwestern Alberta. The damaging effects of the Pincher Creek reservoir fluids on well equipment had been manifested in the discovery well by the rapid and not yet fully understood failure of API Grade N-80 tubing, stainless steel wire lines, and alloy steel fishing tools. Two very unexpected failures in the 9% nickel steel tubing, after only six days of service in production tests, instigated an extensive and continuing investigation to ascertain the probable cause of failure. This discussion presents some of the results obtained thus far which cast a little light on the perplexing behaviour of steels in hydrogen sulphide environments in general, and in sour condensate wells in particular. History of Tubing Failures Walter Marr well No. 1, in which the 9% nickel steel tubing failures occurred, produces from the Madison lime at the depth interval approximately 12,200 to 12,750 feet. The gas-oil ratio is about 26,000 and the gas contains 10.2 per cent hydrogen sulphide and 6.3 per cent carbon dioxide by volume.

Jan 1, 1952

By Jay N. Fairbanks, Richard G. Robinson

This paper discusses a computer program and related formulas for fire fighting responses by coal mine personnel. The computer will interpret the mine air analysis, print reports, and provide relevant graphs allowing quick and accurate responses to coal mine fires.

Jan 1, 1983

By H. W. Leavenworth

Research was conducted by the Bureau of Mines to develop a technique to grow metallic fibers from a sulfide mineral. In this research, chalcopyrite (CuFeS2) was made sulfur deficient, and the remaining sulfur partitioned to the iron in the mineral to liberate metallic copper, or to the copper to liberate metallic iron. The metals formed on the surface as fibers and in the interior as spherical particles. Fiber growth is very fast. Lengths of 3 to 4 cm form in a matter of minutes, and the diameter of individual fibers is less than 1 µm. The mechanism of fiber growth is explained, and the reactions are reversible as predicted. Copper fibers can be made to grow from the surface at 400° C or to dissolve back onto the solid surface and be replaced by iron fibers at 625° C. Growth and dissolution can also be controlled to form copper/iron duplex fibers.

Jan 1, 1974

By Karin Soldenhoff

Recovery of uranium in conventional ion exchange circuits, using strong base or weak base resins containing quaternary or tertiary amine functional groups, is based on an anion exchange mechanism. In saline liquors, chloride competes with uranium for the active resin sites and reduces resin loading. This results in significant negative impacts on the IX process in terms of plant throughput and operating costs. In this paper we present the results of a study on the recovery of uranium from an acidic in situ leach liquor containing approximately 9 g/L chloride. A range of resins was tested, and a high capacity strong base resin was identified with significantly enhanced loading compared to conventional resins. Other process-relevant criteria such as loading kinetics and elution efficacy are also discussed. The process developed was successfully tested during a recent ion exchange pilot plant operated in conjunction with a field-leach trial.

By d&apos, F. Elia

Hot cracking of magnesium (Mg) alloys during welding creates a barrier to enhancing the use of these alloys in automotive applications. As a result, it is imperative to understand the mechanisms responsible for hot cracking of Mg alloy welds in order to develop means of eliminating this problem. In this study, the hot cracking susceptibility of AZ91E and AE42 magnesium alloys were assessed using the moving torch Varestraint test method. Plates of 3 mm thickness were extracted from AZ91E and AE42 ingots and subsequently tested. Quantitative cracking data in terms of maximum crack length (MCL) was used for evaluating the cracking susceptibility. Scanning electron microscopy was carried out. The results suggest that AE42 showed a higher resistance to hot cracking in comparison to the AZ91E alloy. This was attributed to the difference in microstructure between the two alloys. In the fusion zone and HAZ of AE42, the brittle needle-like A1IIRE3 phase was seen to decompose to the more ductile particle-like Al2RE phase, thereby increasing the alloy's resistance to hot cracking. In contrast, SEM fractography revealed that brittle A16Mn and Mg17A112 intermetallic particles segregated to grain boundaries and triggered hot cracking in AZ91E.

Jan 1, 2011

By D. J. Bauer

The Bureau of Mines demonstrated the feasibility of fractionating lanthanide nitrates with a tertiary amine on lanthanum-cerium and thulium-ytterbium pairs. Optimum values were determined for pH, phase concentration, and percent chelation of metal ions in the aqueous phase. Percent extraction is markedly dependent on the concentration of lithium nitrate in the aqueous phase. Selective masking of the heavier element in each extraction system with DTPA or EDTA aqueous-phase chelating agents resulted in lanthanum-cerium separation factors of 8.5 and thulium-ytterbium separation factors of 3.4.

Jan 1, 1966

By Redhead Robert J.

"In 1991, the Canadian Council of Ministers for the Environment (CCME) charged its Waste Management Task Group with developing a nationally coordinated strategy to measure, monitor, and achieve the objective of decreasing the generation of waste (solid and hazardous) by50% from 1988 levels by the year 2000.With the encouragement of the CCME, which viewed hazardous waste as largely an industry problem, a committee, the “Industry Action Group”, representing eleven industry trade associations with a strong interest and involvement in hazardous waste was recruited.The Municipality of Markham, Ontario was also recruited (Appendix 1)."

Jan 1, 1996

By I T. Cameron

The commercial production of copper metal involves a sequence of purification stages. One step of this process eliminates bulk quantities of iron and sulphur from matte Cu2S(FeS to produce blister containing 95.5 per cent copper. This task is traditionally performed in the Pierce-Smith converter, a cylindrical vessel in widespread use throughout the copper industry. Typically, multiple Pierce-Smith converters are arranged along an aisle, simplifying material transfer from vessel to vessel. Materials are moved through the aisle in pots and boats, using overhead cranes. In terms of the overall process, the converter aisle represents a critical processing unitùit contributes significantly to the value added nature of the metal. The aisle is subject to significant process disturbances. Thus, improvements in the operationÆs modes and conditions have a direct impact on process profitability. As with any commercial operation, improvements are always sought to increase process performance. The general approach involves process modelling, followed by an application of control and optimisation theory to this model. The results of such a study are then applied to the real process, leading to improved performance.

Jan 1, 1998

By J. R. Allan

Loki Gold Corporation of Vancouver, B.C. is developing the Brewery Creek Mine, an open pit heap leach gold mine, 55 km East of Dawson City in Yukon, Canada. Mineable reserves are 17.1 million tonnes of ore grading 1.45 grams/tonne, containing 24.8 tonnes (797 000 oz) of gold. Ore processing will employ a cyanide heap leach using run of mine ore. Permitting this mine has drawn significant attention because the heap leach technology, while proven in other jurisdictions, has not been used in Yukon. Engineering design of the heap leach was similar to that for heaps in more temperate climates, with the added issues of permafrost and cold weather operations. Solution balance with seasonal placement of ore and year -round leaching requires very large pond capacity for spring thaw conditions.

Jan 1, 1996

By C. L. Brown

Coal has been transported by belt conveyors in mines for many years; however, only since the beginning of the general mechanization period have complete transportation system of this type been employed. Aside from my complete belt-conveyor transportation systems, belt conveyors are frequently used in conjunction with other transportation. Many early installations, for the most part, were made without standards as a guide. As a result, some States have outlined certain requirements based more or less on experience following mine fires. Correlation of these regulations should result in more uniformity in connection with standardization of regulations. The National Electrical manufacturers Association has published standards for mining-belt-conveyor installations2/ that should be helpful to the coal-mining industry generally. Bureau of Mines Schedule 2F3/ requires certain controls for permissible-belt- conveyor drives, and similar requirements are listed in Bureau of Mines bulletin 514.4/ Committees of the American Mining Congress have prepared much valuable information concerning operation of belt conveyors, and a subcommittee on fire-resistant belting has been active. 5/

Jan 1, 1956

By S. Steinlechner, G. Schneeberger, J. Antrekowitsch

Due to always getting stricter environmental legislations as well as increasing land filling fees the efforts for treating residues from metallurgy are continuously increasing. In case of filter dusts from metallurgical industry, the high zinc bearing electric arc furnace (EAF) dusts or also dusts from secondary copper industry are important sources for the recovery of secondary zinc oxide. Because of low capacities for secondary zinc concentrates (like Waelz oxide) in primary zinc metallurgy, the upgrade of such concentrates to a quality that meets the requirements of high quality (technical) zinc oxide becomes more and more important. This would open the opportunity to break into new markets and use it for example directly in electrolytic galvanizing. Therefore this paper will summarize possibilities for an elimination of halogens from secondary zinc oxides. Furthermore selective volatilization trials, with a synthetic mixture according to the analysis of Waelz oxide, were carried out to remove impurities to achieve an upgraded product quality.

Jan 1, 2011

By A. R. Rule

As part of the Federal effort to help maintain an adequate supply of fertilizer minerals, the Bureau of Mines is conducting research to characterize complex, low-grade western phosphate rock and to develop methods for economic recovery of phosphate. The rock varies from soft, friable, altered phosphatic shale to hard, tightly cemented, unaltered phosphate rock. To supplement current beneficiation by sizing, a flotation procedure was devised that included depression of phosphate minerals with H2SiF6 and anionic flotation of carbonate minerals, followed immediately by cationic flotation of silicate minerals. Application of the procedure to several different ores resulted in phosphate concentrates that ranged from 28 to 31 pct P20S in grade and from 60 to 70 pct in phosphate recovery.

Jan 1, 1977

By J. D. Allen

The Concord Mine Coal Preparation Plant of United States Steel Corporation, located near Bessemer, Alabama, began operations in June, 1950. The basic cleaning circuit consisted of a Chance Cone for cleaning the 2-inch x 3/8-inch fraction and concentrating tables for cleaning the minus 3/8-inch coal fraction. Dewatering of the final product was accomplished with 35-mesh vibrating screens. However, because Concord coal is very friable (Figure 1), 85 per cent passing three mesh and 25 per cent passing 28 mesh, there was a considerable amount of fines passing through the dewatering screens. To recover these fines, the dewatering screen effluent was sent to two 70-foot diameter hydro-separators with the underflow returning to the dewatering screens and the overflow going to a 175-foot diameter thickener for water clarification, (Figure 2). As might be expected, there was a considerable amount of recirculation of the minus 35-mesh coal in this system. This degraded the coal and led to higher moistures. It also resulted in a fines bleed-off of plant water and thickener underflow to a fine-coal settling pond. In 1961, vacuum filters were installed to supplement the screens and to recover the fine coal lost in the bleed-off. The above system resulted in a product moisture of about 20 per cent. Further reduction to approximately 11 per cent was accomplished by drainage from railroad cars during transit to the coke plant. Control of the moisture at unloading was poor because of variations in operating levels and railroad car availability, but since the Concord coal constituted a smaller percentage of the coal previously used at the coke plant, the high moisture and fluctuations did not seriously hamper coking operations.

Jan 1, 1966

By W. C. Whittaker

COMPLETED in November, 1943, at a cost of over $1,500,000, Elk River colliery of the Crow's Nest Pass Coal Company, Limited, has been laid out and equipped for an ultimate annual production of 1,000,000 tons and replaces the recently closed Coal Creek plant, which has been operated by the Company for the past forty-five years. The project has involved the opening of mines in three seams, the construction of a complete set of colliery buildings, including a modern preparation plant of 360 tons per hour capacity, and the laying out of the necessary yard tracks and spur connecting the new development with the Company-owned Morrissey, Fernie and Michel railway, which, in turn, connects with the Canadian Pacific railway at Fernie. The colliery is three and a half miles east of Fernie, B.C., near the southern end of the Crow's Nest coal field, which contains the largest and most important body of coal in the Province of British Columbia. The coal-bearing horizon is the Kootenay formation, present in the form of a syncline covering an area of 230 square miles. Most of the coal seams occur in the lower 2,000 feet of the formation, the covering beds being largely coarse sandstones and conglomerates of great thickness, the presence of which accounts largely for the preservation of the coal measures. James McEvoy, in the report of the Geological Survey of Canada for the year 1900, states that the basin appears to contain a fairly constant coal content of nearly 172 feet in 23 seams of a thickness of one foot or over. Coal has been mined in the Fernie district since 1897 and the first shipments were made from Coal Creek colliery in the following year, over the then newly constructed British Columbia Southern railway. Since that time, a total of over 16,000,000 tons of coal has been produced, an average of 350,000 tons per year. The7ears of peak production were 1910, 1912, and 1913, with an all-time high of 924,000 tons in 1913. The lowest output in the history of Coal Creek was that for the year 1933, when only 60,340 tons were produced, the colliery being closed for some months. Present production from Elk River colliery averages 1,150 tons per day, the output being considerably less than it could be were sufficient man-power available.

Jan 1, 1944

By B. Hart, D. J. Miller, J. T. Francis, M. C. Biesinger, Smart. R. St. C.

Diagnosis of the surface chemical factors playing a part in flotation separation of a valuable sulfide phase requires measurement of the hydrophobic and hydrophilic species that are statistically different between the concentrate and tail streams. Time of flight secondary ion mass spectrometry (ToF-SIMS) can be used to identify sufficient particles of a specific mineral phase for reliable statistics determining a mean value for each species with 95% confidence intervals (1). Using the region of interest (ROI) facility in the Tof-SIMS software, a mass spectrum from each particle, at 1-2 monolayer sensitivity, is recorded and stored. This analysis is reported for a chalcopyrite / pyrite / sphalerite mineral mixture conditioned at pH 9 for 20 minutes in order to study transfer of copper from chalcopyrite via solution to the other two mineral surfaces since this mechanism can be responsible for their inadvertent flotation in copper recovery. Analysis from mineral selection based on specific ToF-SIMS signals (eg. Pb, Zn, Cu, Fe, Fe/Cu) indicated no statistical difference in the copper intensities on pyrite and sphalerite after this conditioning. Principal component analysis (PCA) of the ToF-SIMS imaging data identifies combinations of factors strongly correlated (positively or negatively) in images or spectra from mass spectra recorded at each of 256x256 pixels in a selected area of particles. PCA is a better method of selecting minerals due to multi-variable recognition. It has clearly separated a statistical difference in copper intensities between the sphalerite and pyrite phases. The method has been extended to samples from an operating plant again with excellent phase recognition and diagnostic surface chemistry.

Jan 1, 2004

By C. Burton Clark

The important role of the petrographic microscope in the petrology of refractories is discussed, based on 45 years of industrial experience by the author. Highlights of his career are used to illustrate improvements in equipment and techniques during the period. Two specific investigations are described which emphasize the interrelated use of the petrographic microscope with other instruments such as the x-ray diffractometer and scanning electron microscope. Emphasis is placed on the use of phase equilibrium diagrams for guidance in predicting and interpreting reactions that occur under non-equilibrium conditions in the manufacture and use of refractories.

Jan 1, 1982

By L. Martins

To increase zinc recovery in the concentrate, this investigation performed mineralogical characterization, dispersion studies, bench and pilot-scale flotation experiments and an industrial flotation trial. The objective was to verify the flotation behavior of the silicate zinc ore (calamine type) in the presence of slimes, with the aid of dispersing agents. Characterization studies identified the major minerals in the flotation feed as hemimorphite (calamine), quartz and dolomite. Dispersion tests showed that enhanced dispersion of the particles in the pulp in the absence of reagents occured at a pH range between 8.5 and 12.0. Bench-scale flotation experiments were planned using the statistical tool of complete factorial design at two levels, replicated once. These experiments showed, and were confirmed at the pilot-plant scale, that higher doses of sodium sulfide and polymeric dispersant combined with sodium silicate favored a higher metallurgical recovery. At 6,800 g/t (218 oz/st) sodium sulfide and 6,992 g/t (224 oz/st) polymeric dispersing agent combined with sodium silicate, a zinc grade of 38.4% in the final concentrate was achieved, at an average metallurgical recovery of 72.4%. The industrial trial confirmed the pilot scale results, leading to zinc recovery of 76.1% and a 37.3% zinc grade in the concentrate. Key words: Froth flotation; Flotation reagents; Flotation depressants; Zinc/ zinc ores

Jan 1, 2010

By Andrukaitis. E.

The increasing use of electronic equipment by the Canadian Forces has increased the importance of electric power. A power source that is packed with energy and yet light, small and durable is the common request of military users. However, this needs to be achieved while also addressing the requirements of safety, reliability and low temperature performance. The potential use of fuel cells in a military environment has become a possibility in several areas in the 21st century. Some examples of power source requirements and the materials related R&D required to give better, higher energy power systems in the future will be discussed.

Jan 1, 2005

By N. N. Moebs

The atmosphere in part of an air-sealed coal mine was monitored continuously through a drill hole for oxygen content to determine the effectiveness of sealing a mine against the entrance of air and the major force that caused the phenomenon of mine breathing through the overburden. The differential pressure across the seal and the barometric pressure on the outside also were recorded. A general correlation, obtained between the oxygen level, differential pressure, and barometric pressure, indicates that changes in air pressure are the cause for periodic replenishment of the oxygen in the mine. Mine effluent quality was determined by conditions in many sections of the mine and could not be related to the oxygen level at the drill hole.

Jan 1, 1972