Search Documents

By Mosquera. J.

Tailings Storage Facilities (TSFs) are vast structures that respond to site-specific characteristics, rate of production, placement techniques, and the physical and mechanical properties of tailings. As a common denominator, TSFs are in some degree vulnerable to failure due to liquefaction, poor management, slope instability and/or unusual climatic events. In practice, stability of TSFS is determined by calculating a minimum Factor of Safety (FOS) using the Limit Equilibrium Method (LEM). However, it has been proven that relying exclusively on the limit equilibrium approach is not accurate because it is basically a static method that does not take into account the stress-strain distribution and displacement experienced by the constitutive materials of a TSF. In order to overcome these limitations of the LEM, the finite element method - Shear Reduction Technique (SRT) has been used as a more reliable tool for TSFs stability assessment. This paper presents a comparative stability analysis between an upstream tailings storage facility (UTSF), and a water retention tailings dam (WRTD) under static and pseudo-static states using simplified and rigorous LEMs and the SRT. Additionally, and taking into consideration the intrinsic uncertainty of tailings properties, sensitivity and probabilistic analyses in the form of Monte Carlo Simulation (MCS) and the Point Estimate Method (PEM) are applied to determine the Probability of Failure (Pf) and Reliability Index (ß) of each TSF. It is shown that the friction angle of UTSF?s foundation and the core?s cohesion of the WRTD are the main variables that govern stability. Further analysis shows that the WRTD has a higher reliability index and a lower probability of failure than the UTSF.

Aug 1, 2013

By C. S. Parsons

Introductory The steady advance in the price of lead and zinc in the metal markets of the world during the past few years has resulted in an active search for new deposits of these metals, and to the re-examination of known properties that are now idle. There are a number of deposits of these metals in eastern Canada, the best known of which are the Tetreault mine at Notre Dame des Anges, Que.; the Reader mine on Calumet island, Que.; the Stirling property in Cape Breton, and the Federal mine in Gaspe district, Que. . The author has run concentration tests on the ores from the first three mentioned properties. The ores from Notre Dame des Anges and Calumet island presented problems in concentration which were not successfully solved until the past year. Although considerable experimental work has been done by the Ore Testing Laboratories on the ore from the Stirling mine we have not been successful in developing a satisfactory method of treatment. Character and Types of Ores Metallurgically the lead-zinc ores of eastern Canada may be classified into three distinct types as follows: First: - Ore in which the sulphide minerals are fairly coarsely crystalline and can be freed by crushing to 40 or 60 mesh. The zinc blend has a high iron content (not marmatite) and gives a dark brown colour on grinding. The ores of Notre Dame des Anges and Calumet island, Que., may be cited as examples.

Jan 1, 1925

By C. H. Lau, I. T. Ng

Uniaxial Compressive Strength (UCS) of rocks is an important mechanical parameter for many civil engineering and rock engineering applications such as tunnel excavation, slope stability and foundation design. Macau is one of the world's fastest growing and most densely populated cities, many large and important infrastructures have been being continuously built using pile foundations which are designed to be supported by granitic bedrock. In Macau, the UCS of the granitic bedrock is required almost for every project involving pile foundations and is always measured directly from UCS test in the laboratory. However, direct measurement of UCS requires high quality rock core sample which is not only time-consuming and expensive but also requires high level of operating skill. In view of this fact, estimation of UCS using some empirical correlations will be more practical and efficient because they are relatively fast and economical compared to the direct measurement from UCS test. In the past, some empirical correlations had been established and widely used for estimating UCS of rocks in common engineering practice. However, it has been well recognized that the rock properties are generally varied with sites or geological regions in other words an empirical correlation developed from one region or one country may not be applicable for other regions or countries. Due to the reason that the empirical correlations for predicting UCS for granite are scarce in practice, in this study an extensive experimental program has been performed and a large database containing data such as UCS, Point Load Index (Is50), Schmidt Rebound Hardness (RL), porosity (?), water absorption (S), specific gravity (Gs) and dry density (?d) has been developed. An attempt has been made for developing a new empirical correlation for estimating the UCS of Macau granite. Accordingly, a comprehensive statistical analysis for correlating UCS with Is50, RL, ?, S, Gs and ?d has been performed and a local empirical relationship based on the developed database is proposed for obtaining reliable estimation of UCS for the granite of Macau. Finally, the performance of the proposed correlation is accessed by using another independent testing database developed in this study. It indicates that Is50, RL, ? and S have strong correlation with UCS whereas Gs, ?d have poor correlation with UCS. This study not only proposed a proper predictive empirical correlation for UCS determination for Macau granite but also provides detailed statistical information which is beneficial to engineers for obtaining better characterization of Macau granite.

Jan 1, 2015

By Hassan El-Shall, Ayman El-Midany, Patrick Zhang

Bench and pilot scale testing results suggest that significant improvement in dewatering characteristics of fine particles could be obtained by the addition of fibrous materials. Case studies involving flocculation and dewatering of wastes from phosphate, bauxite, and kaolin processing plants are presented in this paper. Several dewatering techniques were investigated, including sedimentation thickening, filtration, centrifugation, dewatering on screens, and seepage-induced dewatering and consolidation. Advantages and limitations of commercial application of some of the developed techniques arc discussed.

Jan 1, 2004

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 R. Q. Honaker

It has been shown that naturally hydrophobic carbonaceous materials such as coal and graphite can be selectively coagulated and separated from hydrophilic impurities without using oily agglomerants, flocculants or electrolytes. The coagulation occurs at C-potentials significantly higher than those predicted by the classical DLVO theory, suggesting that it is driven by the hydrophobic interaction. In the present work, the energy barriers for the coagulation of a hydrophobic coal sample have been calculated using the extended DLVO theory which incorporates the hydrophobic interaction energy in addition to the dispersion and the electrostatic energies. For the coagulation of minerals present in the coal, the classical DLVO theory has been used for the energy barrier calculation. The results of these calculations provide an excellent correlation with the results of a series of Selective Hydrophobic Coagulation (SHC) tests conducted with run-of-mine coal and graphite samples.

Jan 1, 2004

By K. Cybulski

Coal dust explosions still remain the main hazard in the coal mining sector, notwithstanding their relatively wide recognition compared to other hazards and the development of effective methods of prevention. Coal dust explosions are still the cause of numerous catastrophes, often leading to fatalities. Fortunately, they rarely occur, and it is for this reason that their hazardous impact is often underestimated. This problem in Poland is being exclusively solved by the Central Mining Institute, Experimental Mine Barbara. Here, basic research on the phenomenon of coal dust explosions and prevention methods is carried out, as well as investigations into the causes and circumstances of past accidents. After 15 years of no coal dust explosion accidents in Poland (1987?2002), a few coal dust explosions have recently occurred, with tragic consequences. These events have taken place not only in hard coal mines, where the presence of dangerous coal dust is the result of common production cycle, and safety measures against coal dust explosions are subject to specific regulations, but also in coal-fired power plants. This is of special concern because prior to 1987, such accidents had been been reported only for coal mines and not for coal-fired power plants. In recent years, two dust explosions occurred in Polish power facilities: the Dolna Odra and Turow power plants. In both cases, coal dust explosions occurred in the fuel supply system, but biomass dust was also involved. The explosions caused significant damage to the systems and buildings. This paper gives description and schematics of the regions of catastrophic coal dust explosions that have occurred in recent years in Poland, as well as the results of post-accident investigations, presenting the coal dust explosion hazard at the accident scene The results specify in detail the state of safety measures against coal dust explosions in light of the relevant regulations in force, including amount of deposited coal dust, content of incombustible matter in coal dust, free moisture content in coal dust, state of coal dust explosion safety zones, and state of explosion barriers. The conclusions from the site inspection and post-accident investigations presented enable us to determine locations of explosion initiation, probable ignition sources, range of explosion flames, and explosion barrier performance. A complete elimination of coal dust explosion hazard at the site of dust deposition is practically impossible to achieve. Similarly, a total elimination of ignition source, which may be related to the occurrence of other natural hazards, equipment malfunction or human errors, is impossible. The examples of tragic events that took place in Polish coal mines and coal-fired power plants highlight shortcomings and mistakes made in terms of assessment and prevention measures taken against the coal dust explosion hazard.

Aug 1, 2013

By A. B. Walker

The effects of the injection of dry limestone additives into boilers for the sorption of sulphur dioxide have been studied in pilot and full-scale systems. The effects of such injections on boiler mass particulate emissions as well as collectability characteristics of the fly ash and reaction products are presented. Implications of the effects on the design and economics of particulate collectors, in particular electrostatic precipitators, are discussed.

Jan 1, 1971

By A. Warczok

Metal losses in discard slag are the main factor determining overall recovery. The metals are present both in dissolved form and as matte or metallic inclusions, varying in size from 2 to 1000 µm. Pyrometallurgical slag cleaning usually consists of heating the slag, reduction of oxides and settling of matte/metal droplets. Heating the slag decreases viscosity and accelerates reactions. Reduction of magnetite liberates inclusions and facilitates co-reduction of dissolved metal oxides. A significant amount of the matte and metal is present as very fine metallic inclusions, too small for settling. The coalescence of these matte or metal inclusions is required to remove them from the slag. The developed new concept of slag cleaning combines DC furnace technology with an extra magnetic field for vigorous slag stirring, enhancing mass transfer to the reductant surface, accelerating the rate of reduction, and destabilizing the emulsion of matte or metal inclusions. Intensive slag stirring increases the probability of collision of inclusions, will accelerate their growth and will therefore improve settling. The process is carried out in a patented DC channel furnace, where the liquid metal or matte layer acts as a cathode and the floating coke bed on the slag surface is the anode. In the first part of the furnace, a superimposed magnetic field induces a Lorentz's force causing the slag to start an intensive circular motion. The next furnace zone does not experience any stirring and is dedicated for quiet sedimentation of the inclusions. A mathematical model of gravitational coalescence combined with forced slag motion showed the possibilities of effective removal of copper matte inclusions. The results of laboratory pilot scale tests of continuous slag cleaning showed fast slag reduction and confirmed the improved matte removal from the slag. Conceptual analysis shows the potential use of the technology in various other non-ferrous industries, like for example nickel plants. It is also possible to use this technique batch wise.

Jan 1, 2007

By Atsushi Sainoki

Blast vibration induced by mining activities, such as stope production blasts, could lead to the initiation of seismic events that inflict damage to mine openings. In this paper, the effect of stope production blasts on nearby fault is examined. First, validation of blast vibration attenuation is performed with a numerical model representing a single blast hole through comparison with that calculated from charge-weight scaling law derived from in-situ data. Subsequently, a mine-wide scale model with a fault parallel to a steeply dipping, tabular ore deposit that is mined out with sublevel stoping method is generated, and the stopes are extracted and backfilled with static analysis to simulate burst-prone conditions on the fault. Based on the stress states, dynamic analysis is performed, in which blast vibration is applied to grid points on a stope wall on the hanging wall side. This assumes 9 blast holes located close to the wall, and blast-induced particle velocities that consider the positional relationships between the assumed blast holes and the stope wall are applied. During the dynamic analysis, blast sequence is considered, and stress states and shear displacement on the faults are examined. It is found from results that, after a rise in normal stress on the fault due to compressive waves induced by the blasts, the normal stress decreases because of the reflection of the compressive waves on the fault. The reduction in the normal stress due to the reflected waves is found to be large enough to cause the fault to slip. The results also show that the level of normal stress eventually keeps decreasing with time as the blast sequence proceeds and that an increase in shear displacement on the fault is accompanied by a decrease in normal stress. This study clarifies the mechanism by which blast vibration causes the fault to slip. In addition, the simulation technique to apply blast vibration that takes into account blast sequence and the locations of blast holes to a stope wall is developed.

Aug 1, 2013

By W. P. Nash, T. E. Mccandless

"Abstract - Detrital minerals of upper mantle origin occur in Holocene conglomerates, pediments and antmounds, and in Oligocene conglomerates in the Green River Basin of southwestern Wyoming. The minerals are derived from disaggregated eclogite and peridotite, and are similar to minerals found in mantle- derived igneous rocks such as kimberlite and lamproite, the primary host rocks for diamond. The Green River Basin bisects the lamproite fields of the Leucite Hills (Wyoming) and Kamas (Utah) and overlies the Archean Wyoming craton, which makes the region favorable for diamond occurrence. Lamproite is the favored host for the indicator minerals because unusual high-Fe salitic diopside macrocrysts from the antmounds and from the ~1 Ma old Leucite Hills lamproites to the northeast are compositionally identical. The salitic diopside is uncommon in other igneous rocks and could be a new indicator mineral for use in lamproite exploration. The Green River Basin indicator minerals are eroded from the ~29 Ma old Bishop Conglomerate, whose source area is the Uinta Mountains to the south. No continuous mineral train exists between the Uinta occurrences and those in the Green River Basin. Assessment of the minerals using established and new geochemical criteria indicate that they formed in an oxidizing upper mantle and were transported to the surface by either kimberlite or lamproite. The existence of cogenetic diamond is unlikely based on the mineral chemistry, but selective removal of diamond indicator minerals through weathering and fluvial transport cannot be excluded. Diamonds and mantle garnets are present in the northeastern Uinta Mountains, but they originated as part of the Diamond Hoax of 1872. A representative mineral assemblage from the true igneous host of the indicator minerals is required to fully establish their economic potential. Post-Oligocene erosion and Pleistocene glaciation have hindered efforts to locate a bona fide igneous source for the indicator minerals. Résumé - Des minéraux détritiques provenant du manteau supérieur ont été trouvés dans des conglomérats, des pédiments et des monticules de fourmis de l’Holocéne, et dans des conglomérats de l’Oligocène du Green River Basin, au sud-ouest du Wyoming. Ces minéraux sont issus du démantellement d’éclogites et de péridotites, et sont semblables aux minéraux trouvés dans des roches ignées provenant du manteau, comme les kimberlites et les lamproïtes. Ces dernières sont les roches hôtes du diamant. Le Green River Basin recoupe les champs à lamproïte de Leucite Hills, au Wyoming et de Kamas en Utah, et il surmonte le craton archéen du Wyoming, connu pour la présence de ses diamants. La lamproïte est l’encaissant privilégié pour les minéraux «indicateurs» parce que des macrocristaux exceptionnels de diopsides salitiques riches en Fer, provenant des monticules de fourmis et des lamproïtes de Leucite Hill (~1 Ma), au nord-est, ont des compositions identiques. Le diopside salitique est rare dans les autres roches ignées et peut être un nouvel indicateur dans la recherche de lamproïte. Les minéraux «indicateurs» du Green River Basin proviennent de l’érosion du Conglomérat de Bishop, daté de ~29 Ma, dont la zone source est représentée par les Uinta Mountains, au sud. Aucune continuité des gisements minéraux n’existe entre les affleurements de Uinta et ceux du Green River Basin. La détermination des minéraux, utilisant des critères géochimiques anciens et récents, indique qu’ils se sont formés dans un manteau supérieur oxydant et qu’ils ont été remontés à la surface soit dans des kimberlites, soit dans des lamproïtes. La genèse du diamant n’est que peu liée à la chimie minérale, mais le lessivage d’indicateurs minéraux du diamant par altération météorique et par transport fluviatile ne peut être exclu. Des diamants et des grenats mantelliques sont présents dans le nord-est des Uinta Mountains, mais sont associés avec le Diamant Hoax de 1872. Un assemblage minéral représentati"

Jan 1, 1996

By R. C. Gilmore, J. F. Brune

"Pulverized limestone rock dust used in United States underground coal mines to prevent and suppress coal dust explosions must easily disperse by forces of a methane or coal dust explosion. Moisture in the mine environment causes caking of the dust. Colorado School of Mines researchers performed dispersibility tests in a full-size explosion test drift. Tests included conventional, hydrophobized, and rock dust approved for German mines. Conventional and German standard rock dust products partially agglomerate, which may not be effective in suppressing a coal dust explosion, while hydrophobic rock dust retains better dispersibility.INTRODUCTIONA coal dust explosion devastated the Upper Big Branch mine in 2010 resulting in the death of 29 miners, the worst mining accident in the United States since 1972. The explosion propagated through approximately 65 km of active mine workings, but was extinguished in areas that had been properly rock dusted (Page, 2011). Researchers have long studied and established the ability of inert limestone rock dust to suppress coal dust explosions, see Richmond et al. (1975), Cybulski (1975), and Sapko et al. (2000).To be effective, rock dust must contribute to a total inert content of > 80% by weight and 100% of rock dust particles must pass through an 850 µm sieve, while 70% of the rock dust must be finer than 74 µm. This is established in US regulations 30 CFR §75.2. Dry rock dust is a nuisance that prevents mining work downwind from rock dusting activities. To overcome this problem, dust manufacturers have proposed applying the rock dust as a wet slurry or foam. After drying, manufacturers expected the slurry or foam-applied dust to have the same explosion suppression capabilities as dry-applied rock dust.Researchers at the Colorado School of Mines (CSM) designed and built a full-scale, underground Explosion Test Facility (ETF) at the CSM Edgar Experimental Mine in Idaho Springs, Colorado about 20 miles west of the CSM Golden, Colorado campus. To disperse the different rock dust products, researchers produced an air pressure pulse using a mesh array of PETN detonation cord. This method is simpler, more reproducible and safer than other methods considered, including methane-air explosions and a compressed air cannon. The detonation cord blasts produce a wind velocity of 30 to 50 m/s, the minimum velocity at which coal dust explosions can propagate, based on research by Nagy (1981) and Cybulski (1975)."

Jan 1, 2019

By R. P. van Hille, N. Mooruth

Remediation of acid rock drainage (ARD) was performed within a linear flow channel reactor (LFCR) via a floating sulphur biofilm (FSB). A full sulphur species material balance was conducted in order to characterize the sulphide oxidation. The reactor was able to achieve an 82% and 93% conversion of sulphide with a hydraulic residence time of 2 and 5 days respectively. 92% and 55.5% of the converted sulphide reported to the biofilm as sulphur for the 2 and 5 day residence times respectively. The mass transport limitations within the biofilm were identified via a dissolved oxygen gradient profiling system.

Jan 1, 2011

By F. Khomamizadeh

In this study, deep cryogenic treatment was applied to A319 cast aluminum samples. Although the cryogenic treatment didn't have any significant effect on mechanical properties of the well degassed and fluxed samples, but the tensile strength of the samples containing a considerable amount of gas and shrinkage defects was improved surprisingly, This improvement was attributed to the strengthening of the a-aluminum matrix which slows down the propagation of the existing defects. There was no significant increase in the hardness after cryogenic treatment, The abrasion resistance of the alloy was improved after cryogenic treatment, by developing a homogeneous protector shield, composed of abrasive grains penetrated into the soft aluminum matrix and kept tight.

Jan 1, 2005

By P. M. Daignault

"Fording Coal Limited is one of Canada's largest producers of metallurgical coal for the export market. Medium- to highvolatile coals are mined at its Fording River operations in southeastern British Columbia. This paper discusses some of the mine design and production related problems encountered, and how they have been resolved. Other aspects of the operation such as geography, geology and standard mining methods employed are also covered.IntroductionFording Coal Limited was formed in 1968 to mine and market metallurgical coal resources held by the company in the East Kootenay region of southeastern British Columbia<1>. The company, at its Fording River operations, holds approximately 19,635 hectares of coal lands, having an estimated resource of 3.5 billion tonnes of metallurgical coal. Total reserves are approximately 520 million tonnes.Fording Coal is owned 600Jo by Canadian Pacific Enterprises Limited and 400Jo by Cominco Limited. Cominco itself is owned approximately 540Jo by Canadian Pacific Enterprises. The company, originally staffed and managed by Cominco, has been independent since January 1978, with its own board of directors, management, staff and employees. The head office is in Calgary, Alberta. The Fording River operations are located in British Columbia, approximately 70 km north of the Crowsnest Pass, near the Alberta/ British Columbia boundary, only 150 km by air and 320 km by road from Calgary.A contract was signed in 1969 with the Japanese steel mills to provide 45. 7 million tonnes of metallurgical coal over fifteen years, commencing in 1972, at an annual rate of 3 .05 million tonnes per year. The mine is presently expanding annual production capacity from the original 3.0 million long tons (3.05 million tonnes) to in excess of 5.0 million tonnes.Concurrent with this production expansion, a vigorous marketing effort has diversified Fording's customers to include additional countries in the Pacific Rim area. Three cleaned coal products are now marketed compared to the single ""standard blend"" product originally shipped to satisfy the Japanese contract. The product specifications are listed in Table I."

Jan 1, 1985

By Harry J. Cain

Introduction The property of Pioneer Gold Mines of B. C., Limited, is located in the Lillooet mining district of British Columbia, on Cadwallader creek, 54 miles distant by motor road from Shalalth, a station on the Pacific Great Eastern railway. Milling by the present Company was commenced in 1924, a small amalgamation plant, consisting of a crusher, Bryan mill, and plates being operated until 1928. Tailing from this plant was impounded and later treated in the 100-ton continuous counter-current decantation cyanide plant which was erected during 1927-28 and placed in operation during May of 1928. A second cyanide plant, employing continuous counter-current decantation, having a nominal capacity of 200 tons, has been erected during the past few months and was put into operation during September of the present year. The ultimate capacity of the combined units of the present mill has not been determined, but it is expected to be much in excess of the rated capacity. The Ore The ore, as received at the mill, consists chiefly of quartz carrying free gold, with small amounts of pyrite, arsenopyrite, and pyrrhotite in evidence, though probably amounting to less than one per cent of the total. Some gold is very closely associated with the sulphides. The country rock is a basic igneous rock, probably an augite diorite. Near the vein it is highly altered to sericite, which slimes readily on grinding, and does not settle very well. The quartz is of two types, clear and ribbon. In the latter, the ribbons, which are not much thicker than paper, consist of shattered sulphides. In crushing this ribbon quartz, breakage is often along the streaks, exposing these shattered faces to advantage in subsequent treatment. While gold is the metal for which the ore is mined, some silver is also present and is paid for by the mint. It is, however, unimportant from a commercial viewpoint. From the standpoint of crushing and grinding, the ore might be termed &apos;medium &apos;hard&apos;.

Jan 1, 1932

By J. W. Gregg, P. M. Dranchuk, D. L. Flock

"From preliminary investigations it has been observed that although evaporation losses may be estimated by comparing single values of certain physical properties of crude oils and their evaporation residues, such techniques possess little accuracy unless both the evaporation process and the variation of the property as a function of the process are completely known. The accuracy of estimation may be increased somewhat through the comparison of property mid-per-cent curves. Further increases in accuracy are possible if bottoms yield •curves rather than mid-percent curves are used. The use of both the mid-percent and bottoms yield curves however involves a prohibitive amount of effort in most cases. Examinations of distillation bottoms from Hempel type distillations carried to end points just short of the cracking point have indicated that these bottoms are not appreciably affected by the evaporation process. It was further observed that bottoms of identical API gravity, obtained from a crude oil and its evaporation residues behave as if they were pure components which were unaffected by evaporation. Based on these observations Hempel distillation bottoms of equal API gravity were obtained for a crude oil and its various evaporation residues from API gravity bottoms yield curves. The volume percent of these bottoms in the crude oil and its residues were used to calculate the evaporation losses suffered by the crude in order to yield the various residues. The results indicate that, although further refinements in technique are required, it is possible to calculate evaporation losses with an accept-able degree of accuracy through the use of this method."

Jan 1, 1960

By D. Stone, N. J. Aslin, W. Webb

In today&apos;s modem copper electro-refineries, increasingly higher average current densities are being employed. With these increases many refineries are approaching their limiting current density. The nearness of the average operating current density to the limiting current density has placed increasing emphasis on the need to maintain an even current distribution. This paper explores the importance of maintaining even current density and discusses the factors, processes and practices that are necessary to achieve and maintain high quality production at high operational intensity.

Jan 1, 2005

By L. Jones, S. R. Lawrence, A. R. Holloway

Whilst dense medium separation is best known for its ability to concentrate diamond and coal deposits, the process is now being employed in southern Africa as a pre-concentration step to improve the economics of platinum group metal and nickel ores. DMS plants built for these industries (such as the 1600tph unit at Tati Nickel, Botswana), are spearheading an expansion in this area by reducing mine and process operating costs yet maintaining economic metal recoveries. This paper provides an overview of DMS technology and examines the economic benefits available to North American operators and projects, with recent case studies as reference.

Jan 1, 2009

By P Hulteberg

In this article, an integrated catalytic reactor design approach to produce PEMFC-quality hydrogen is evaluated. The design is based on a high level of heat exchanging perfonned internally, highly active noble metal catalysts and a woven wire mesh catalyst support system. It consists of an integrated steam refonner and a catalytic burner section, a water gas shift section and a preferential carbon monoxide oxidation section. The reactor design is described and experiments perfonned to evaluate the two reactors built are reported. The two reactors have a maximum output of 3 Nm and 10 Nm3 hydrogen/h respectively. In the larger unit, a total of six fuels, three gaseous (methane, natural gas and liquid propane gas) and three liquid (naphtha, ethanol and methanol), were evaluated. The larger unit was also used to investigate how variations of parameters such as steam-to-carbon ratio in the steam reforming part of the system and the relation between oxygen and carbon monoxide in the preferential carbon monoxide oxidation affect the reactor perfonnance. The smaller unit was used, after implementing automatic control, to run a system life time test for 480 h. The refonner system perfonned according to specifications on almost every aspect.

Jan 1, 2005