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By W. B. Evans, D. P. Taylor

"ANFO has two major disadvantages as an explosive low density and no water resistance. ANFO can be blended with more dense, water-resistant explosives to form ""Heavy ANFO"". The use of emulsion or slurry explosives as a matrix is an attempt to correct deficiencies on the basic ANFO while maintaining cost effectiveness.This paper will deal with four main topics.1. Product description, general properties, strengths and weaknesses.2. Technology of ""Heavy ANFO"" , the emulsion matrix concept and the range of products.3. Relative performance and economics in various rock types.4: Current status in Canada and worldwide, and the expectations for future use.IntroductionANFO has been in use for roughly three decades and remains the explosive of choice where conditions are suitable. ANFO has not become the universal explosive - despite its undoubted superiority in cost effectiveness - because it has serious flaws as an explosive. The most serious of these flaws are the low density and absence of water resistance in ANFO. Low density implies a low concentration of explosive energy in a borehole. The amount of energy available can be increased by. adding an energetic material, generally aluminum, or by drilling more holes. Both solutions add considerably to the over-all costs. The absence of water resistance in ANFO is inherent and can only be overcome by changing the fundamental nature of the product. The history of research in the explosives industry since the advent of ANFO is mainly the story of the various attempts to overcome one or both of ANFO's shortcomings.Many technologies and products have been developed to compete against ANFO, among them slurries, emulsion s and the so-called Dense ANFOs (ANFO with an extra nitroalkane liquid sensitizer). None of them was cost-competitive with ANFO so their market penetration has been limited to wet holes or specialized applications. The exception to this result is Heavy ANFO. The aim here was to have the best of both worlds, the high density and water resistance of emulsions or slurries plus the low cost of ANFO. The concept is very simple. ANFO is about 50 % air, roughly 30% in the prills and 700,10 between the prills . The air in the prills provides the necessary sensitivity but the air between them is waste volume. If one fills this volume with a high density, waterproof product, the resultant mix will be denser and more water resistant than ANFO and with very little added cost. This basic concept was invented by B. Clay in the 1970s and is covered by Canadian Patent No. 1 115 959. The water resistance and/or density of the mix can be tailored by changing the emulsion level. Because Heavy ANFO is relatively inexpensive while providing good in-hole densities and water resistance, it can compete successfully against all other bulk products. It competes against ANFO and Al / ANFO by allowing pattern expansion and reducing over-all costs while it competes against emulsions and slurries on price."

Jan 1, 1987

By S. C. Tadolini

"Roof bolts are the primary means of roof support in underground mines in the United States. Presently, post installation loads are measured on about 10% of the expansion anchor and combination bolts by using standard torque wrenches that Unit the accuracy of the measurements to about ±30%. No system has been available for measuring the loads generated on full-column resin grouted bolts. Mine roof bolts are long, slender, non-uniformly sized, roughly forged, and placed in a corrosive environment, creating obstacles for researchers trying to utilize ultrasonic reflection techniques to measure strain. A complete measurement system has now been developed by the U.S. Bureau of Mines, Denver Research Center. This system is being used successfully in determining loads measured on expansion anchor and combination bolting systems, examining the transfer mechanics of full-column, resin-grouted bolts, and measuring loads generated on bolts in an underground roadway support system.IntroductionMillions of roof bolts are used each year to provide structural support in underground U.S. metal, non-metal, and coal mines. Approximately 45% of the bolts used are expansion anchor, 45% are resin-assisted combination or full-column resin-grouted, and 10% are friction anchored. The effectiveness of these bolting types is dependent on a number of factors including rock density, bolt length, in situ stresses, rock properties, bolt pattern, installation tension, etc. When implementing expansion anchor and resin assisted combination bolts , installation and post-installation tension, or load, is a major determinant of support quality and subsequent behaviour of the reinforced roof. The method by which these systems carry roof loads is well understood and documented(1,2).The importance of these installation and long-term bolt tension measurements is well recognized and are required in the federal government regulations(3). A statistical sample of the bolts, lout of 4 during installation and lout of 10 inby the last open crosscut, is required to be measured using current torque wrench technology. The disadvantages of this system are the disturbance and weakening of the anchorage and limitations of accuracy to approximately ± 30%. The method by which resin-grouted bolting systems carry roof loads is much less understood, mainly because testing procedures used to evaluate point-anchor systems are not effective on resin-grouted bolts.Due to these problems, the U.S. Bureau of Mines designed a measurement technique that provided a highly accurate, low cost-per- bolt system that led to the development of ultrasonic pulse echo instrumentation. The original system was designed to measure the tension only on expansion anchor bolts. Recent developments and system modifications have permitted measurements on resin-assisted and full-column resin-grouted bolts. The use of these types of support systems has been increasing steadily in underground coal mines.The development of this instrumentation has provided laboratory and field results that help to explain the mechanics and relationships between the applied loads and the interaction between the grouted bolt system consisting of the bolt tendon, grout, and rock."

Jan 1, 1990

By J. A. Rogers

"The Arthur W. White Mine (formerly Dickenson Mine) is a structurally controlled, hydrothermal gold deposit. A gold producer since 1948, it has, to December 31, 1990, processed 6.9 million (m) tons (T) of ore grading 0.45 ounces per ton gold (oz/T Au). As of December 31, 1991, Proven and Probable Ore Reserves were 3.2 m. T. at 0.32 oz/T Au. The mine is located just east ofPlacer Dome Inc. 's Campbell Mine, within the Cochenour-Gull.rock Lake deformation zone. It is situated on the hanging-wall side of a southeast-plunging anticline in a sequence of metamorphosed Archean volcanic, sedimentary and plutonic rocks of the Red Lake greenstone belt. Ore-bearing structures, found mainly within basaltic rocks, are brittle within greenschist-facies rocks to the northwest, but become more ductile toward the southeast, in amphibolite-facies rocks. Within and proximal to these structures, carbonate and arsenopyrite alteration decreases, whereas biotite, actinolite, pyrite and pyrrh otite all increase to the southeast.Ore and shear structures occur symmetrically about the northwest-trending, steeply southwest-dipping, flattening foliation . The three most common ore trends are on average: (A) northwest trending with a 55 degree to 85 degree dip to the southwest; (B) north-trending with a 40 degree to 50 degree dip to the west; and (C) due east-west-trending with a vertical dip. In general, the dominant direction of economic gold concentrations are explained and thus predicted by considering deformation style (brittle or ductile), rock anisotropies such as bedding and lithological contacts, and direction/magnitude of relative block movement. Direction ""A"" can be found adjacent to both right- and left-handed faults. Direction ""B "" occurs with dominantly right-handed systems and direction ""C"" is found with predominantly left-handed movement. Major faults active prior to, during, and after ore formation can have offsets in the order of 2500 feet. Movements along these faults were transpressive while their conjugate breaks were dilatant, thus creating zones for alteration and ore solution emplacement. A series of faults , each with offsets up to 30 feet were established under lower temperature brittle conditions during late- to post-ore formation. In more complex zones, formed during more ductile deformation, these faults controlled the localized geometry and, thereby, the depletion and enrichment of ore shoots, causing a high nugget effect.Although an important aspect of production planning and monitoring, grade control is also very important within a complex ore zone so that the nuggets are not missed. Detailed observation of structure at the hand-sample scale and detailed mapping at the stope scale give valuable clues to interpreting the structures on a mine-wide scale. Determining the relative movement along fault structures is very important so that using an action-reaction- type logic, potential dilatant areas can be predicted and targeted for development and diamond drilling."

Jan 1, 1992

By Nabeel Khan

Annual oil production from the Canadian Oil Sands in Northern Alberta has been rising for several decades, and more ore and overburden are excavated each year from an increasing number of open pit mines. Overburden meeting certain specifications will be used to dam tailings and fill open pits, but the remaining material must be stored in overburden storage structures (OBSS). Well-designed overburden storage structures are more stable and cost less in the short- and long-term. The purpose of this paper is to explore OBSS designs that will be stable yet economical in the short- and long-term. The geological background of the site is briefly discussed, including the effect of each of the main geologic layers (recently deposited till and muskeg, Clearwater Formation clay shales, McMurray Formation oil sands, and the Devonian limestone) on the slope stability of the OBSS. Cost is considered in the analysis when balancing between minimizing costs (steeper slopes) and acceptable factors of safety (flatter slopes), all the while considering the financial consequences of failure. Potential failure planes are identified and probabilistic analysis is conducted on the critical failure surface. The variations in the factor of safety caused by varying pore water pressure, friction angle, and cohesion, are plotted and discussed.

Jun 1, 2012

By A. Singh

Two alloys Mg96.9Zn2.7Ho0.4 and Mg93Zn6Ho have been processed by direct extrusion at 300°C and 200/230°C to produce various microstructures containing icosahedral quasicrystalline phase with different grain sizes. The alloys were mechanically tested in tension and compression. The mechanical properties were related to the grain size and microstructures studied by transmission electron microscopy. The extruded alloys showed a mixture of nano-sized icosahedral and monoclinic Mg4Zn7 phase, as well as icosahedral phase particles a few hundred nanometers in size distributed in the matrix. Coarse icosahedral phase particles several micron in size also remained after extrusion. The alloys Mg96.9Zn2.7Ho0.4 and Mg93Zn6Ho extruded at the same temperature of 300°C produced very different grain sizes of 15 and 3 µm, respectively. The alloy Mg96.9Zn2.7Ho0.4 extruded at 200°C and Mg93Zn6Ho extruded at 230°C produced grain sizes of 0.7 µm and 1.5 µm, respectively. Both the alloys showed yield stresses of about 300 MPa in both tension and compression with elongations of about 18%. Hall-Petch parameters are calculated for the alloys.

Jan 1, 2006

By H. C. Cooke

"This paper has reference in a general way to the region extending from the north shore of lake Buron to the northern limit of the elliptical-shaped area generally known as the Sudbury Basin, and more especially to the district lying south of the Basin (Fig. 3). Attention is concentrated mainly on the structure of the district and, as space does not permit of much geological description, it is assumed that the reader has some knowledge of the general geology. The accompanying table outlines the sequence of the rock formations according to the most recent available information; for further details the interested reader may consult the publications of the various authors mentioned in the paper.STRUCTURE OF THE SEDIMENTARY ROCKS SOUTH OF THE SUDBURY IRRUPTIVEThe rocks south of the Sudbury irruptive, excluding certain intrusives, are, in order from north to south:(1) A band of basic lavas.(2) A band of well-bedded greywackes and quartzites, long termed the McKim greywacke.(3) The Copper Cliff formation, with McKim greywacke' both to the north and south.(4) The Ramsay Lake conglomerate.(5) A thick quartzite formation.All these rocks strike approximately east-northeast, dip steeply south, and generally face south, though there are local exceptions."

Jan 1, 1954

By W. A. Jones

THE Ross mine, a subsidiary operation of Hollinger Consolidated Gold Mines, Limited, is situated near the north end of lot 1, concession 2, Hislop township, Ontario. The property comprises the north half of lot 1, concession 2, and the south one-third of lot 1, concession 3. It is readily reached by a good motor road from the village of Ramore, 7.5 miles to the southeast on the Temiskaming and Northern Ontario railway. The-mine has been developed to a depth of 900 feet and the current daily production rate is about 260 tons. From the inception of operations in March, 1935, until December 31st, 1942, 455,720 tons of ore with a total value of $4,169,-316 have been milled. The silver to gold ratio of 1.48 to 1 is unusually high for Ontario gold mines. The deposit is interesting because the relationship between hydrothermal metamorphism and three successive stages of fracturing and mineralization is marked with considerable clarity. During the past seven years, detailed geological maps of the mine have been kept up to date, many thousands of feet of diamond-drill core have been logged, and numerous thin and polished ore sections have been studied. The present paper describes the structure and mineralogy of the orebodies.

Jan 1, 1944

By J. F. Nie

Mechanical properties of precipitation hardenable magnesium alloys depend critically on the chemistry, structure, morphology, orientation and distribution of strengthening precipitates. It is therefore important to gain an improved understanding of these information and their correlations with mechanical properties. Our recent studies indicate that additions of 1-2 wt% of Zn to a Mg-6wt%Gd alloy result in a substantial enhancement in precipitation hardening and in creep resistance. If the strength and creep resistance of the resulting ternary alloy are to be further enhanced for commercial applications, then a detailed characterisation of the strengthening precipitates in these alloys is required. In the present study, the precipitates formed in a Mg-6Gd-1Zn-0.6Zr (wt%) alloy, peaked aged at 250°C, have been characterised in detail using transmission electron microscopy and 3-dimensional atom probe field-ion microscopy. It is found the peak-aged microstructure contains a dense and uniform distribution of precipitate plates that form on the basal plane of the matrix phase and are typically less than 1 nm in thickness. Detailed analyses of the structure and composition of these basal precipitate plates will be presented and discussed in the context of previous work on other Mg-RE¬Zn alloys of similar compositions.

Jan 1, 2006

By H. C. Cooke

"The Eustis mine, which was discovered in 1865, lies about 6 miles southwest of the city of Sherbrooke, Quebec, in lots 2, 3, and 4, range 9, Ascot tp. The mine was operated almost continuously from 1865 to 1937, under vanous owners.The ore was pyrite with varying amounts of chalcopyrite, a small amount of zinc blende and galena, and a low content in gold and silver. Parts of it ran quite high in copper, but the mine average would probably have been between 3 and 4 per cent. The high percentage of pyrite made it profitable to separate the ore into a copper concentrate and a pyrite concentrate. The latter was shipped away for manufacturing sulphuric acid, or was treated in a plant erected in 1887 at Capelton by the Nichols Chemical Company.The ore is a replacement of mica schist, which in turn was formed by the shearing of rhyolite flows. Ore also replaces the 'green rock', a term locally applied to carbonatized mica schists. The ore contained numerous 'horses' and smaller fragments of country rock, in all stages of replacement, ranging from those whose character was quite distinct to those whose ancestry could only be detected by an indefinite banding preserved in the sulphides."

Jan 1, 1954

By I. M. Santos Moraes

The control of minor impurities (mainly As, Sb and Bi) in copper refineries has been a great challenge. Caraiba Metais' copper refinery produces a very high quality copper, registered in LME as grade A, and recognized as amongst the top ten in the copper world. At Caraiba's Tankhouse Bi and Sb are controlled by means of electrolyte bleed-stream removal after partial decopperizing in a set of electro-winning cells (liberators). Another way of reducing the Sb and Bi content in the electrolyte is by means of the arsenate precipitation chemistry. It is well known that the use of high arsenic concentrations in copper refinery electrolyte has the advantage of causing most of the bismuth and antimony to report in the anode slimes. However, the use of such mechanism of control may contribute to other undesired problems such as antimony and bismuth precipitation in the bulk of the electrolyte, what may cause severe contamination problems. This paper describes a period when some cathode contamination with Sb occurred at Caraiba Metais' Copper Refinery. It also presents an analysis of several process parameters related to the problem, the possible causes for the contaminations as well as the actions taken to correct the problem.

Jan 1, 2007

By M. Stelter

Since the first years in copper electrorefining natural products have been used as so called "additives" in the electrolyte. Glue as one of these additives offers a lot of different reactions with the metal ions and also with other additives like thiourea in the electrolyte. For a deep understanding of the effect of these additives it is important to know the routes of possible reactions in the electrolyte as well as the basics of electrocrystallization. Using this knowledge the interpretation of nodulation or inclusions of electrolyte in the cathodes in copper electrorefining is easier than before. Setting up on physical and chemical properties of the electrolyte and the additives practical investigations of the effects of additives in copper electrorefining and their impacts on copper crystallization and cathode quality are presented in this paper. Chemical deposition of glue against time and temperature are only few of the effects that are mainly caused by the use of natural products. In fact parameters like anodic and cathodic polarization are strongly affected by the additives as well as the effects of the additives are strongly affected by current density. This second part of the paper presents results concerning interactions of the above mentioned parameters.

Jan 1, 2007

By H. T. Michels

Recent laboratory studies show that several bacteria, known to be human pathogens, die when they come in contact with copper and copper alloy surfaces. The amount of live bacteria drops by several orders of magnitude, to zero, on copper alloys in a few hours. In contrast, no reduction is seen in the concentration of live organisms on stainless steel during the six-hour test period. Aluminum painted and coated surfaces and plastics would show behavior similar to stainless steel and show no effect. Coatings and other surfaces claiming to be antimicrobial showed little to no effect. These results suggest the selection of copper alloys for surfaces exposed to human touch can materially assist in reducing the transmission of infectious organisms. In order to make antimicrobial claims in the United States, the approval of the US Environmental Protection Agency (EPA) is required. The EPA-required efficacy testing is described and the test results are summarized. It is anticipated, that once regulatory approval is obtained, that this will facilitate the introduction of antimicrobial copper alloys in hospitals, nursing homes and other healthcare facilities, as well as schools, and public buildings. Some of the application and barriers, to entry into the healthcare markets are mentioned.

Jan 1, 2007

By Manouchehr Oliazadeh

Talc is used as a gelating, diluting, antimould and softening agent in the pharmaceutical industries. This article reviews efforts made for producing pharmaceutical grade talc from a mine located in the west of Iran, called Masoud Abad. Reaching to the pharmaceutical standards, was the principal goal of the talc beneficiation. Methods such as flotation and leaching were applied to eliminate the impurities. Considering to the negligible Fe content of the ore, the major impurity was calcium carbonate and to some extent dolomite. Depressants used in froth flotation were dextrine, quebraco and sodium silicate. Variation of collectors such as oil petroleum, paraffin, stearic acid were also used. After optimization of the effective parameters, followed by two stages of flotation (rougher and cleaner) acid leaching process was also applied as a complementary step to remove the impurities. CaO impurities in the sample was 11.63% which reduced to 1.03% after two stages of flotation, and finally reached to 0.03% CaO by leaching process. This figure is more lower than the world pharmaceutical standards (i.e. <0.6 % CaO). The highest recovery was 55% at the best conditions. Other impurities (i.e.As, lead, heavy metals ,?) which were at standard levels, confirmed by the authorized health organizations.

May 1, 2001

By L. Byszynski

The results of a three month evaluation of the application of EMEW® technology at the KGHM Glogów II Smelter tank house bleed stream are presented. The current, conven¬tional electrolyte decopperization process has some limitations, including: only a fraction of its production is commercial grade cathode copper, significant operating costs, low current efficiency, low current densities resulting in low copper depletion rate, and arsine gas and sulphuric acid emission. The EMEW® cell technology developed by Electrometals Technologies Ltd. can overcome many of these limitations. Tests were performed on a pilot EMEW® installation comprising 30 cells at ambient temperature on electrolyte bleed, using current densities between 100 and 600 A/m2 , with copper concentrations between 45 and <1g/dm3. Results showed that a high grade copper can be obtained to the level of 7 g/dm3 of copper concentration in electrolyte. The use of EMEW® technology allows the direct and efficient recovery of over 85% of the copper contained in the bleed electrolyte. Glue & thiourea addition were tested in order to improve the parameters of the copper depletion process. The behavior of Arsenic and Bismuth was observed and a means for their elimination from the system proposed. On-line copper concentration monitoring is proposed to improve control and performance.

Jan 1, 2007

By P. Bonadia, A. Tabereaux

Nearly all aluminium smelters are increasing the potline amperage to achieve higher aluminium production. In some instances the higher amperage operation has a significant negative impact on shortening the lifetime of aluminum electrolysis cell cathodes due to loss of the protective sidewall cryolite ledge freeze and too rapid penetration of the cell bottom refractory lining by cryolitic bath components due to the higher temperature isotherms. Thus Cathodes require careful thermal modeling of the cathode relining designs and improved refractory materials to allow greater heat loss from the sidewall to preserve a stable sidewall ledge freeze at higher amperages, and the selection of optimum refractory barrier materials to control the penetration and reaction of bath into the cathode bottom refractory and insulation lining. This requires an understanding of the reaction mechanisms and product formation for molten NaF enriched bath and alumino-silicate refractories. It is desirable to use dense, low porosity refractory fireclay firebricks, or similar materials with a sufficiently high silica content to promote the formation the mineralogical phase albite, NaAlSi3O8, that significantly increases the viscosity of the melt which slows the diffusion of reactive species in the melt and thereby retards further bath penetration.

Jan 1, 2004

By M. Fooladi Mahani, M. R. Izadpanah

The knowledge of the thermal shock resistance of refractory materials is of outmost importance due to their wide range of applications in various industries, namely; ceramics, oil refinery, thermal insulation, nuclear power, chemical and petrochemical industries. Thermal shock resistance is measured in terms of the number of cycles that a refractory material can withstand when subjected to sudden temperature changes. This property is measured experimentally by heating a sample of the material and cooling it in a known environment then the number of cycles it withstands this treatment without spalling is a measure of its thermal shock resistance. Although this method of experimentation has long been the practice, but it is both expensive and time consuming. Various studies have been carried out to predict this vital property, however, the rang of applications are limited. The present study employs a test rig by which temperature distributions in magnesite samples are accurately measured. This information plus other results obtained from relevant tests on related properties are used to develop a model which predicts the number of quench cycles withstand by different materials when subjected to sudden temperature changes. The comparison of the theoretical values using the solution of the presented model with experimental data for different materials having different thermal resistance shows a closed agreement.

Jan 1, 2004

By Par G. Jönsson, Joachim von Scheele, D. S. Sarma, Mukul Goyal

Dust from flue gas cleaning systems at iron and steel production is frequently considered as a waste problem, but it is actually a potential raw material source. By using a technology like the oxyfuel based OXYFINES technique, it can be melted into a suitable form. The product from this processing, however, needs to meet the requirements of a recyclable raw material, here particularly a top-charged blast furnace feed. The present work has been focused on characterization of the product produced from these dusts by OXYFINES technology. The investigation has been carried out on samples of processed dusts from a European integrated steel mill. It was done by means of chemical analysis, density measurement, light optical microscopy, X-ray diffraction, scanning electron microscopy combined with energy dispersive spectroscopy, and micro indention hardness measurement. Special attention was paid to the presence of zinc, an element that might be harmful while recycling the material (e.g., in a blast furnace). The results show that the product contains four different regions with different morphologies and properties in the material, which are discussed in detail. The overall conclusion is that by processing the dusts in this way, a raw material suitable for recycling in a blast furnace can be obtained.

Jan 1, 2004

By Jamal Asfahani

Abstract - Natural gamma ray well logging, an effective tool in geophysical prospecting, is used to investigate the radioactive and phosphatic layers in the Khneifiss mine in Syria. The interpretation of the gamma ray measurements, using numerical methods of analysis developed previously and applied successfully in some phosphatic areas in Syria, make it possible to define precisely the phosphate thickness from place to place in the study area. This technique has been successfully applied while studying seven boreholes in the area. Sixty-three core samples from phosphatic layers in the boreholes have been analyzed, using gamma ray spectrometry for the determination of P2O5 , U, Th, and K. Good correlation between P2O5 content and U concentration has been found. The total count gamma logs correlate reasonably well with the U core analysis, suggesting that radioactive equilibrium exists in the U decay series. These gamma logs can be therefore used effectively to quantitatively map the distribution of P2O5 and U. The characteristics of both subsurface phosphatic sand and phosphatic rocks have been investigated and outlined using a statistical approach. The affinity of uranium to some trace elements such as V, Sr, Cu, and Ni has been verified using correlation matrices of these elements.

Jan 1, 2002

By A. Jeffkins

Visibility is restricted when operating load haul dump vehicles resulting in a number of serious accidents in the Ontario Mining Industry. One of the leading causes of these accidents is the inability of the equipment operator to see clearly people, objects or hazards around the machine. Previous line of sight testing by the research team found specific machine characteristics were responsible for blind spots and impaired visibility. In order to identify feasible design modifications a computer simulation program, Classic JACK 3.1, was utilized. Program features include human factors analysis, which allows evaluation of line of sight and operator posture in order to decrease risk of musculoskeletal injury. Research within the virtual computer environment consisted of a Visibility Audit and a Target Audit in order to quantitatively determine how certain components of the LHD design affected the line of sight around the vehicle. Results indicate that modifying the LHD light brackets, engine profile, cab posts and other components will enhance visibility. The addition of cameras located on the front and rear of the vehicle were able to enhance the operator?s sight lines to previously obstructed areas. Modifications to seat height and the operators orientation both improved sightlines and decreased risk factors associated with back and neck musculoskeletal disorders.

May 1, 2003

By Anna Maria Venezia

Bimetallic Au-Pd catalysts supported on amorphous silica-alumina (ASA) with vary amount of alumina (0, 8, 14, 28 and 100%) were prepared by the simultaneous reduction of palladium and gold precursors by ethanol in the presence of the polyvinylpyrrolidone (PVP). X-ray diffraction and X-ray photoelectron spectroscopy analyses indicated formation of alloyed Au-Pd particles. Ammonia temperature programmed desorption measurements were performed to monitor the acid strength and the amount of acid sites on the catalysts after their reduction with 10%H2/Ar at 573 K for 1h. The effect of the support acidity on the catalytic activity was investigated in the simultaneous hydrogenation (HYD) of toluene (T) and naphthalene (NP) in the presence of dibenzothiophene (DBT). Coke formation was also determined. Under the selected conditions (P = 5.0 MPa, T = 523 K, WHSV = 41.2 h-1), all the catalysts were resistant to poisoning with 113 ppm of S (as DBT). The hydrogenation activity of toluene and the HDS activity of DBT were found to correlate with the concentration of the medium strength acid sites. The enhancement of the HYD activity and the S- tolerance was related to modifications of the electronic properties of the metal atom upon interaction with the Brönsted acid sites and upon intermetallic interaction.

Oct 1, 2003