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By S. Jordanov

The nature of processes that take place on top of copper bearing grains during the suppression of copper acid drainage from mine tailings was studied on a grain model. Cyclic voltammetry (C.V.) was employed as an experimental technique suitable for indirect measuring of copper leaching. Experiments were done in sulfuric acid (pH=2) at electrodes that progressively approach the real situation during acid main drainage, starting with Cu-metal, then with CuO and finally with CuO covered with CaSO4. Oxidation was found to be the only process that takes place on metallic copper electrode anodically polarized up to 2 V vs. Cu/CuSO4 reference electrode. Dissolution is intensive and reaches up to 50 mA.cm-2. When the same was repeated, but on CuO electrode, anodic currents were some 4 times lower than on the bare metallic surface. This indicates that the electrode material is not completely oxidized to copper(II)oxide and the Cu(O) or Cu(I) residues are oxidized during the anodic polarization. This explains the diminished dissolution. Dissolution is further restricted at electrodes covered with CaSO4. It is some 20 times lower than on the bare oxide electrode. When the second layer of CaSO4 was applied, anodic currents were another 15 times lower. Total decrease of anodic currents when transition is made from Cu-metal to CuO covered with 2 layers of CaSO4 reaches up to 7.500 times. C.V. measurements produced a proof that mechanical blockage is the way how lime prevents leaching of copper bearing grains in immobilization experiments referred elsewhere.

Jan 1, 2007

By R. Pakalnis, H. Miller, Madill. T.

"This paper describes a methodical approach to the estimation of the orientation and the magnitude of in-situ stresses. The study was performed at the Ruttan Mine, Sherritt Gordon Mines Ltd. , a 6,000 T.P.D. underground operation, located in northern Manitoba, Canada. It involves an initial estimate to be made based upon: structural interpretation • virgin stress measurements conducted in other areas (world wide, regional)The verification of the prevailing stress regime was made by conducting CSIRO hollow inclusion(1) overcoring measurements. The current cost for a virgin stress determination is about $7000 per measurement(2) and the difficulty encountered in attaining a good reading is high. This paper will describe the analytical procedures employed at Ruttan in evaluating the in-situ stress magnitude and orientation based on three overcore tests. It is proposed to perform an additional six measurements in order to verify the following results:Vertical stress = av (MPa) = 0.027 by depth (m)Major principal stress = o! """" 2.5 xav (340°/-20°)*Intermediate principal stress = a2 - 1.2xav (070°/0°)Minor principal stress = a3 """" o.8xov (160°/-70°)IntroductionThe Ruttan Mine of Sherritt Gordon Mines Ltd., a 6,000 T.P.D. underground operation, is located in northern Manitoba, Canada (Fig. I). The Ruttan copper-zinc orebody is a multi-lensed, steeply dipping (70 degrees) en-echelon deposit. Individual lenses have a maximum strike length of 350 m with widths varying from 7 m to 61 m. The mining method is o pen stoping with delayed backfilling and extends from surface to 860 m below surface."

Jan 1, 1985

By C. Harold Riches

This article is directed co a commentary on the patent system in its relation to the public interest. As man gained supremacy over his environment, he could devote progressively increasing portions o his time to improving his standards of living. In the history of the human race, we have advanced from the hollowed floating log to the modern steamship of the present age; from the sickle and flail to the reaper and combine; from the trumpet and drum as a means of communication co the telegraph, telephone, and radio; from the horse and ox cart to the automobile, truck, aeroplane, and train; and so on ad infinitum through the list of inventions on which are based the industrial and political economies and standards of living we enjoy today. It has also been a long road from the day of the alchemist and his closely guarded secrets to the era of the patent system and its storehouses of knowledge open to the world. The alchemist and the craft and merchant guilds closely guarded their secrets. In fact, they largely opposed innovations on the grounds that they might injure profits and restrict employment. In these days of unrest, with great clamour out of doors for radical changes in our political and industrial economies, it may not be untimely to examine one of the keystones which support the economic structure we know as the free enterprise system, the system which is predicated upon the right of the individual to own property. Many, through impractical idealism, ignorance, confused thinking, or blind political prejudice, advocate the substitution of ownership by the State ? for the right of ownership by the individual. As civilization has advanced to the high standards of living we enjoy today through the efforts of a comparatively few inventors, the patent system which has provided the incentive that created the inventions on which our industries and our employment are based is fully understood and appreciated by a comparatively small percentage of our people. As a result, the patent system, as a keystone in our free enterprise economy, is an apt target for destructive criticism, with the thought, possibly, that by eliminating or drastically restricting the several rights to individual ownership one by one, ownership by the State will progressively replace ownership by the individual.

Jan 1, 1949

By P. C. Patnaik

Performance of industrial gas turbine engines in terms of power output, reduced cooling and efficiency have been continuously increasing in parallel with aero gas turbines due to the advances made in the development of new materials, protective thermal barrier coatings (TBCs) and the advanced diagnostics to monitor service induced problems such as hot corrosion, thermal and thermo-mechanical fatigue and other operational issues, Environmental attack (hot corrosion or high temperature oxidation) is a common degradation mode in the hot section of the gas turbine, Hot corrosion occurs when Na or K bearing compounds in the environment or in the fuel combine with other contaminants such as S and Pb or V to form corrosive sulphates or vanadates thus attacking the protective oxide on the turbine airfoil, These problems pose far more threat to new turbine engine materials such as directional solidified, single crystals and ceramic matrix composites (CMCs). The CMCs due to their increased temperature capability, when used in the combustion chamber, are likely to reduce the peak temperatures attained during combustion and therefore provide the benefits of reduced emissions of oxides of C and N, These issues will be reviewed critically and their impact will be assessed on gas turbine lives. With respect to alternate fuels, past experience has shown that utilization of residual oils and coal derived fuels in gas turbines have resulted in complex deposition and corrosion processes, In recent years biomass derived alternate fuels have been used either through a gasification cycle or through direct firing of the biomass derived liquid fuel with a view to reduce Green House Gases (GHGs) and improve the climatic conditions. In both cases, the resulting high temperature corrosion processes (in the presence of alkaloids in the fuel) are also very complex, leading to premature removal of hot section components, Technology solutions mitigating these fundamental problems will be reviewed and solutions presented.

Jan 1, 2005

By Sadough vanini Ali

Charpy impact energy of functionally graded steels produced by electroslag remelting in crack divider configuration has been modeled in various strain rates. It has been well known that majority of materials indicate different behaviors under different strain rates and temperatures. Therefore, modifying the elastic-plastic model considering the effects of strain rates and temperature gives us an acceptable prediction of these composites behaviors in impact test. In this investigation, graded steel was divided in to several layers in which the layers have the same strains under the impact. Constitutive equation describing the flow stress variations as a function of strain rates and temperatures, have been used to express the stressstrain behavior of layers. The parameter values of constitutive equation determined for all the layers via using the boundary conditions based on composite graded behaviors which were the characterized ferrite, austenite, bainite and martensitte phases. Consequently by applying the rule of phase mixtures and ascribing the impact energy of each layer to the area of stress-strain curve of the same layer, the whole impact energy of composite is the sum of layers impact energy with considering the layers volume fraction.

Oct 1, 2011

By M. M. Papic

"This paper describes the Sasol coal liquefaction process, as used in South Africa. It covers coal supply, coal gasification, gas purification, Fischer-Tropsch synthesis, the major utility systems involved and the economics of the process.IntroductionThe Sasol coal liquefaction process is based on Fischer-Tropsch synthesis of liquid fuels from carbon monoxide and hydrogen, which are in turn obtained by gasification of coal with steam and oxygen. The process is shown schematically in Figure I.The first step in the process is coal preparation, in which the coal is crushed and screened to a 3-50 mm size for gasification on one side and to -3 mm size for steam and power production on the other. Oxygen needed for coal gasificatoin is produced in the air separation plant.Coal is gasified under pressure by steam and oxygen in the Lurgi gasification plant, where raw, impure gas is produced . The raw gas is first washed in a scrubber with a circulating gas liquor, heat is then recovered from it in a waste heat recovery boiler and the gas is further cooled for purification. Water-insoluble materials (tar oils) in the gas liquor are separated from aqueous solution and sent to tar refining for the recovery of tar products. The aqueous portion of the gas liquor goes to a Phenosolvan solvent extraction process, where phenols and ammonia are recovered. Water then proceeds to the effluent treatment plant.The scrubbed and cooled raw gas goes to a Rectisol gas purification plant, where all components other than hydrogen, carbon monoxide and methane are removed as completely as possible by absorption in refrigerated methanol. The acid gases (CO2, H2S) stripped from the methanol in the Rectisol unit are processed in a Stretford plant for recovery of sulphur. Regenerated methanol is returned to the process. The purified synthesis gas is passed to the fluidized-bed Synthol reactors, where Fischer-Tropsch synthesis reactions take place.The synthesis products are recovered in a product recovery unit as separate streams of decant oil containing higher-molecular- weight hydrocarbons, light oil comprised of lower-molecular- weight species, the aqueous stream containing water solubles, a C3/C4 stream, a C2 stream , a methane stream and a hydrogen-rich stream. Most of the hydrogen is recycled to the Synthol reactors; a major portion of the methane is reformed to hydrogen and carbon monoxide for recycle; the C2 fraction goes to an ethylene plant; and liquid streams proceed to the product refinery.The product refinery is used to upgrade and purify the Synthol products to specification fuels and chemicals.Sasol l, the first coal liquefaction plant in South Africa , was built in 1955. It is still operating and has a product output of about half a million tonnes per year. The Sasol II plant is in a commissioning stage and will be in full operation in 1981. It is about five times the size of Sasoll. It uses over 12 million tonnes of coal and produces more than 2 million tonnes of saleable products annually (1,2,3). The Sasol llI plant, which is a mirror image of Sasol II, is under construction and scheduled for completion in 1983."

Jan 1, 1981

By Donald P. MacKinnon

"This paper is a commentary on selected trends within the transportation industry.In general, innovations are taking place within all modes of transport (road, rail and water) serving the industrial minerals industry which will affect future distribution patterns, methods and costs. Significant technical innovations in the transportation of solids by• pipeline will also appear, perhaps in the near future, permitting the transport of specific commodities, including some industrial minerals. However, the timing and magnitude of the commercial exploitation of solids pipelines are heavily dictated by marketing factors and distribution system logistics, as well as by the innovations likely to take place within competitive modes of transport. Competitive technological developments will include increased ship capacities, improved bulk-handling facilities, larger and specialized bulk-handling rail equipment, unit trains, containerization, larger ""off-highway"" vehicles and greater inter-modal integration. Equally significant are some ""soft-ware"" techniques such as the growing interest in total distribution cost concepts. However, the impact of the developments will not be spread uniformly over all Canadian industrial minerals."

Jan 1, 1967

By A. M. Hadian

The use of dolomite refractories in steel making and cement industries has advantages over other basic products particularly in countries where this type of refractories is produced. Due to existence of high-quality dolomite deposits in many regions of Iran, there is a good potential for producing dolomite refractories in the country. This study focuses on the effect of such additives as iron oxide and alumina on hydration resistance and density of Iranian dolomite. It was found that addition of Fe2O3 is more effective than Al2O3 on increasing density as well as resistance to hydration of dolomite.

Jan 1, 2004

By Ron Jessulat

"IntroductionBrunswick Mining and Smelting Corp. Ltd. is a IO 500 tid base metal producer. Development is carried out by Jarvis Clark MJM-21 3-boom development jumbos, using Tamrock E400, 410 and 550 pneumatic drills. Typical drift size is 13 ft by 18 ft with a 12-ft advance per round. Blast holes are 1 ½ in. in diameter while reamed holes are 3 in. in diameter. AN/FO is the principal blasting agent, being loaded by C-I-L model60R intermediate loader. The detonators are NONELS and DETINELS. Sulphide dust explosions occur during blasting when dusts from certain minerals such as pyrite and pyrrhotite are ignited by name from the detonating shots. The result is a secondary unwanted explosion with a characteristic shock wave and name front that are very destructive to mine services such as ventilation ducting, electrical cable, and ventilation control doors.A typical reaction in the Brunswick orebody occurs according to the chemical formula:4FeS 2 + IIOs-2Fe2O3 + 8SO2 + 3458--(Enright , 1988)The hematite (FeO3) is deposited as a red dust in the blast area while the toxic sulphur dioxide gas (S00 contaminates the underground workings . The presence of S02 gas disrupts production until it is purged from the area by the mine ventilation system or dissipates slowly in those areas where the vent ducting has been melted by the name front or torn down by the shock wave.Sulphide dust explosions exact a high economic toll. Direct costs in damaged materials and wages are probably exceeded by the value of lost production and disruption to the mining cycle. In addition, the health and safety concerns associated with sulphide dust explosions cannot be ignored."

Jan 1, 1993

By Lin Li, Ahmad Ghahremaninezhad

"In this paper, the electrochemical behavior of ferric and ferrous couple on the pyrite surface was studied by application of the chronoamperometry technique in an acidic solution at room temperatures and atmospheric pressure. The effects of the pyrite origin, ferric and ferrous ions concentration on the electron transfer kinetics of Fe3+/Fe2+ reaction were probed. Tafel behavior of all the test conditions were developed. The results showed that the ferric-ferrous reaction on pyrite electrodes with different origins have a common mechanism, despite different reaction kinetics. The exchange current densities of the redox reaction have the same magnitude of about 10-5 A·cm-2, which is far lower than the value reported for the gold and platinum electrodes, but larger than that of the chalcopyrite electrode. The cathodic transfer coefficients are between 0.4 and 0.5, while the anodic transfer coefficients appear unusual with the lowest value being 0.23. It was also demonstrated that an increase of one order of magnitude of iron concentration has no clear effect on the exchange current density and cathodic transfer coefficients of Fe3+/Fe2+ redox reaction.INTRODUCTIONPyrite, FeS2, is mostly considered as a gangue mineral which frequently coexists with valuable minerals and metals, such as gold, copper and nickel. Its separation from valuable minerals can be a costly process (Chandra & Gerson, 2010). In refractory gold ores, the fine gold particles are locked inside the pyrite structure. Oxidative leaching of pyrite is a hydrometallurgical method to destroy the structure of pyrite and expose the fine gold particles to the cyanide solution in the downstream cyanidation circuit. Pyrite oxidative leaching can be achieved by oxidation of pyrite via oxygen and ferric ion(McKibben & Barnes, 1986). In fact, pyrite oxidation by oxygen and ferric is a significant source of acid mine drainage(AMD), which adversely causes serious environmental problems(V. P. Evangelou, 1995).The pyrite oxidation mechanism is accomplished in three consecutive steps: (i) pyrite is oxidized by oxygen and ferrous ion formation (Eq. 1); (ii) ferrous oxidation by oxygen and ferric ion formation (Eq. 2); (iii) pyrite oxidation by means of ferric ions (Eq. 3). Hence, both oxygen and ferric participate in the pyrite oxidation process (Moses & Herman, 1991):"

Jan 1, 2016

By J. Chlan

"Dryer DescriptionProctor and Schwartz Continuous Conveyor DryerThe Proctor and Schwartz Continuous Conveyor Dryer has been in operation since July 1958, and comprises six unit• - an 8• wide single conveyor with roller extruder, insulated housing, type 304 stainless steel circulating and exhaust fall system, steam heating coils, temperature controls and discharge crusher rolls. Entire dryer dimensions are 52’ x 12'0""weighing 53,000 lbs,Extruder rolls - setting is 1/8"" (Drive 3 HP 1800 RPM) clearance off the extruder screen.Conveyor - consists of 151 interlocking pans, measuring 8"" x 8' (2 HP 1200 RPM) One Exhaust Fan (5HP - 900 RPM)Steam Coils -- l"" steel pipe - with steel fins -- each coil measures 16' 2’’- 64 coils in the No, 1 Compartment- 64 coils in the No, 2 CompartmentDryer OperationThe yellowcake slurry at 28% solids is pumped to an 81 x 8' Peterson Filter. The filter media presently being used is a Neotex 4372 blanket, being 100% staple fibre nylon, 12 oz per square yard with air porosity of 9 CFM's. The cake discharge at 45 - 50% moisture falls into the roller extruder. Extrusions are formed by forcing the material by rolls through a perforated plate moving back and forth and depositing the spaghetti-like extrusion on onto the dryer-conveyor.The conveyor now carries the extruded material through the heating chamber•, The feed end of the dryer will be referred to as No. 1 Compartment, with temperature control set at 280""F. The circulating fans take the hot air off the coils and circulate the heated air through the perforated openings in the dryer conveyor pane, After passing through the set of steam coils and circulating fan in No, 1 Compartment, the material then goes through No, 2 Compartment where the temperature is set at 305'F, Final material then discharges through a set of crusher rolls set at ~"". Moisture of final dried product runs at less than 2%.The dryer conveyor load is usually run to a 3"" - 4"" depth load. Conveyor speed at approximately 90 minutes for load to pass through. Load onto the conveyor is controlled by boot level and speed of the 8' x 8' filter. The dryer steam coils are water-washed twice a month."

Jan 1, 1972

By L. K. Mireku

"Abstract - The Halfmile Lake South Deep zone, Bathurst Mining Camp, New Brunswick, was discovered by Noranda Inc. (Exploration) as a result of a 3-D seismic survey in 1998 and the subsequent drilling of ten diamond-drill cores. The deposit consists of massive, breccia, and stockwork Pb-Zn-Cu sulfide minerals, and is hosted by a volcano-sedimentary sequence belonging to the overturned Ordovician Tetagouche Group. Epiclastic rocks and interbedded fine-grained felsic pyroclastic rocks dominate the stratigraphic footwall. Locally, crystal-rich felsic tuffs and subordinate epiclastic rocks comprise the immediate stratigraphic hanging wall. The entire stratigraphic sequence was intruded by quartz-feldspar porphyritic intrusions, and cut by intermediate and basic dikes. The volcanic and sedimentary rocks can be discriminated geochemically using trace element ratios such as Zr/TiO2 and Nb/TiO2, despite intensive alteration and cleavage development. These ratios indicate that four protolith volcanic compositions exist: rhyolite, dacite, andesite, and basalt. The aphyric and feldspar- and quartz-phyric volcanic rocks are dacitic and rhyolitic in composition; epiclastic rocks have trace element ratios consistent with dacitic compositions. Pearce element ratio diagrams, general element ratio diagrams, and petrographic observations demonstrate that the rhyolitic volcanic rocks exhibit evidence of albite, potassium feldspar, and quartz fractionation, dacitic volcanic rocks exhibit little evidence of any fractionation, and epiclastic sedimentary rocks exhibit evidence of quartz sorting only. Hydrothermal alteration is best represented by the presence of phengitic muscovite and daphnitic chlorite. Minor calcite occurs in the stratigraphic hanging wall, deep in the stratigraphic footwall, and in post-mineralization dikes, and thus is not interpreted to be part of the causative hydrothermal event. Element additions and losses during alteration have been used to determine net alteration reactions, and these have been used to identify alteration parameters that are independent of other forms of alteration and fractionation/sorting, and which can be used to guide exploration. These parameters include: a bulk hydrolysis measure, (2Ca+Na+K-2CO2)/Al; a muscovite alteration measure, K/Al; an albite destruction measure, Na/Al; a chlorite alteration measure, (Fe+Mg-S/2)/Al; a chlorite composition measure, (Fe-S/2)/Mg; a sulfidization measure, S/Ti; and a carbonatization measure, CO2/Ti. With the exception of the carbonatization measure, these alteration parameters define a distinct lateral and vertical zone of intense hydrothermal alteration in the stratigraphic footwall of the deposit, and demonstrate that the epiclastic rocks are predominantly chlorite altered, and the volcanic rocks are predominantly muscovite altered. Within the alteration halo, element additions of Fe and H, and element losses of Na are characteristic. Potassium was added to muscovite-altered rocks, but subsequently removed from chlorite-altered rocks. The results from this study demonstrate that metamorphism and deformation have not significantly obscured hydrothermal alteration signatures."

Jan 1, 2006

By Lei Pan, Roe-Hoan Yoon

"Sea water flotation is becoming a reality due to shortages of fresh water. To better understand the mechanisms involved in sea water flotation, we have studied the effects of KCl and MgCl2 on the surface forces present in the wetting films of water formed on hydrophobic surfaces. The measurements have been conducted using the force apparatus for deformable surface (FADS), which is capable of measuring both the surface and hydrodynamic forces responsible for bubble-particle interactions. The results obtained with the gold surfaces hydrophobized with butanethiol (C4SH) show that the wetting films of Ultrapure water do not rupture despite the relatively high water contact angle (??= 80o) and the presence of a long-range hydrophobic force with a decay length (D) of 25 nm in the film. The film is metastable with its equilibrium thickness (he) at 140 nm, where the repulsive double-layer force is equal in magnitude to the capillary force as shown in Figure 1. The film loses its metastability and ruptures in a 10-2 M KCl solution, in which the double-layer force decreases substantially due to the decrease in Debye length (?-1) while the decay length of the hydrophobic force remains as large as 23 nm.The effects of MgCl2 has also been studied using a C4SH-coated gold surface with a water contact angle of 87o. It has been found that in a 10-4 M solution double-layer force decreases due to the decrease in the negative ?-potentials and Debye length, which should help destabilize the wetting film. However, the film remains stable due to the decrease in the decay length of the long-range hydrophobic force from 45 nm in Ultrapure water to 14 nm in the MgCl2 solution. Thus, the results obtained in the present investigation support the view that the difficulties in sea water flotation may be due to the presence of MgCl2 rather than the presence of NaCl in sea water (Ramos, et al., 2013)."

Jan 1, 2016

By K. D. A. Whaley

Abstract -The Captain North Extension deposit consists of five sulfide lenses hosted in cherty and chloritic metasediment that is bounded by quartz-eye rhyolite and laminated rhyolite . Lens 2 consists of sphalerite and galena with silver-rich tetrahedrite in chert. Lens 3 contains massive pyrite, with chalcopyrite and minor gold, gradational to minor pyrite in a chloritic metasediment . The other lenses are unexplored. The sulfides occur as beds, fracture infills, and disseminated grains. Reserves are estimated at 207 555 tonnes grading 7.38% Zn, 2.76% Pb, and 91.81 g/t Ag. The deposit is isoclinally folded, dips steeply west, plunges 50 degrees south, and is faulted out to the north, where drag folding has reversed the plunge. Minor cross-faults contain talc and sericite. High sphalerite but low pyrite abundances result in poor responses to standard electromagnetic techniques. Lens 3, which contains more pyrite than Lens 2, responds better to induced polarization and allows detection. Geochemical anomalies are found in a nearby swamp and stream, but an impervious till cover inhibits the development of soil anomalies.

Jan 1, 1992

By K. D. A. Whaley

The Captain North Extension deposit consists of five sulfide lenses hosted in cherty and chloritic metasediment that is bounded by quartz-eye rhyolite and laminated rhyolite. Lens 2 consists of sphalerite and galena with silver-rich tetrahedrite in chert. Lens 3 contains massive pyrite, with chalcopyrite and minor gold, gradational to minor pyrite in a chloritic metasediment. The other lenses are unexplored. The sulfides occur as beds, fracture infills, and disseminated grains. Reserves are estimated at 207 555 tonnes grading 7.380/0 Zn, 2.76% Pb, and 91.81 g/t Ag. The deposit is isoclinally folded, dips steeply west, plunges 50 degrees south, and is faulted out to the north, where drag folding has reversed the plunge. Minor cross-faults contain talc and sericite. High sphalerite but low pyrite abundances result in poor responses to standard electromagnetic techniques. Lens 3, which contains more pyrite than Lens 2, responds better to induced polarization and allows detection. Geochemical anomalies are found in a nearby swamp and stream, but an impervious till cover inhibits the development of soil anomalies.

Jan 1, 1992

By D. W. Heard

Electrospark Deposition (ESD) is a low heat-input, high energy density, micro-welding process. The short pulse duration and high-pulse frequency, in combination with the small amount of material transferred during each pulse, results in the evolution of extremely rapid cooling rates, believed to approach 105-106 °C/s [1]. This rapid solidification event results in the refinement of the microstructure to the nanostructured or amorphous level [2, 3]. Figure 1 displays the resultant microstructure of an Al-17%Si alloy deposited by the ESD process. Furthermore, it was determined that the microstructure of the deposit remained unchanged after subsequent layers were welded onto the presented layer. Freeforming of materials is a rapid prototyping process in which the deposited feedstock is built-up to the desired geometry in a near-net shape manner. Figure 2 displays the automated set-up employed produce three dimensional freeformed objects via multiple deposition trials of the ESD process. The automated XYZ table is equipped with CNC software to transform CAD renderings into three dimensional tool paths. Figure 3 displays an Al-12Si freeformed gear (2" diameter, 12 teeth) produced by the ESD process, prior to removal from the substrate. An SEM analysis of the freeformed component showed that the microstructure did not coarsen during the deposition of subsequent layers during the freeforming process, as depicted in Figure 4, resulting in the production of a bulk nanostructured component. This paper represents a summary of the capabilities of ESD to fabricate advanced materials possessing refined microstructure. In particular, results on the microstructural evolution obtainable for various wear-related systems will be presented. In addition, the feasibility of using the ESD process to freeform three-dimensional objects via multiple deposition passes will be presented and accompanied by a characterization of the properties of the freeformed component. [1] R. N. Johnson, "ElectroSpark Deposition: Principles and Applications," in Society of Vacuum Coaters, 2002, pp. 87-92. [2] J. Milligan, D. W. Heard, and M. Brochu, "Formation of nanostructured weldments in the Al-Si system using electrospark welding," Applied Surface Science, vol. 256, pp. 4009-4016. [3] S. Cadney and M. Brochu, "Formation of amorphous Zr41.2Ti13.8NilOCul2.5Be22.5 coatings via the ElectroSpark Deposition process," Intermetallics, vol. 16, pp. 518-523, 2008.

Jan 1, 2010

By N. Moelans, I. Bellemans, K. Verbeken

In this work, we present a phase field model to simulate the facetted crystallization of Fe3O4 in a quaternary FeO-Fe2O3-Cu2O-SiO2 melt under different partial pressures of oxygen. An important focus in creating more realistic phase field models is the incorporation of the thermodynamic driving forces in multicomponent multiphase-field models by coupling to thermodynamic databases. The diffusion of FeO, Fe2O3 and Cu2O is considered. The ratio of FeO/Fe2O3 at the upper boundary is in equilibrium with the oxygen fugacity of the atmosphere, while conserving Fe. Two-dimensional simulations are performed with different varying oxygen fugacity in the atmosphere. For the considered composition range, the growth velocities of the spinel crystals increase with decreasing oxygen fugacity. INTRODUCTION Crystallization of silicate melts has its applications in geology, pyrometallurgy and glass making. In pyrometallurgy, the solidification of slags influences the freeze lining behaviour (Campforts et al., 2007) and the cooling of slag after tapping (Durinck, Jones, Blanpain, & Wollants, 2008). Modeling of silicate melt crystallization is frequently done on the macroscopic level, using thermodynamic equilibrium calculations to determine the fractions of all phases as a function of temperature. The Factsage software and database package (Bale et al., 2016, 2009, 2002) already proved its usefulness in pyrometallurgical applications, for example to model the phase mixture after solidification of a stainless steel slag (Durinck et al., 2008). Crystallization of phases typically results in complex morphologies on the mesoscale, e.g. dendrites or facetted growth. On this mesoscale, the phase field concept has proved to be a very powerful tool (Moelans, Blanpain, & Wollants, 2008) for modeling crystallizing microstructures, because it can treat arbitrarily complex interface shapes with minimal mathematical complexity. In contrast to macroscopic models, the diffusion profiles and crystallization kinetics can be described as well as the morphology of individual crystals. First, Kobayashi (Kobayashi, 1993) simulated a growing dendrite in a pure undercooled metallic liquid. Then, Warren and Boettinger (1995) simulated a dendrite in an isothermal system considering a binary alloy. The extension to multi-phase systems was done by Steinbach et al. (1996). This was further extended by Tiaden, Nestler, Diepers, and Steinbach (1998) to a framework with coupled diffusion and phase field equations in multi-component systems.

Jan 1, 2019

By H. J. Ni, M. Y. Huang, S. W. Chen

The effects of several fluxes on purification, microstructures and properties of A00 aluminium have been studied. The experimental results and analyses indicate that many cracks and large porosities exist in the surface film above the melt purified by C2Cl6 and that the film is floe and mostly composed of AhO3 and pure aluminum, which carries many carbon particles and AlCh not fully volatilized. And then over 50% of the all-melting residue is pure aluminum, which is one of the major reasons for high melting loss. Moreover, because of a mass of gas bubbles and a state of seethe, there exist many inclusions which size is under l0µm in the microstructure of A00 aluminum purified with C2Cl6 or fluxes containing C2Cl6- With this purifying method, the aluminum crystal grains are extended along the radius that was observed firstly and the average crystal size of A00 aluminum are about 100µm~150µm. In addition, small size inclusions have little affected on tensile strength and micro inclusions under l0µm have little affected on elongation.

Jan 1, 2006

By Andreea Catalina Gluhoi

The oxidation of propylene and methane has been investigated over two series of Au/MOx/Al2O3 and Au/MIOx/MIIOx/Al2O3 catalysts (M, MI, MII =Li, Rb, Mg, Mn, Ce, Zr). Whereas the effect of the presence of MOx or MOI x/MOII x on the oxidation of methane is relatively small, a large enhancement in activity is observed for propylene oxidation. Synergistic effects have been observed by combining ceria or a transition metal oxide (high oxygen storage capacity) with an (earth) alkali metal oxide.

Oct 1, 2003

By S. Torres, J. Álvarez, R. Castillo, R. Fuentes, C. Sandoval, R. Parra, Myakalwar A. K., M. Velázquez, J. Yáñez, D. Sbarbaro

Rapid analytical assessment in copper mining industry is a limiting factor for operational purposes and for the improvement of processes. The present work aims to review the analytical assessment in the copper industry utilizing emerging spectrochemical techniques such as laser induced breakdown spectroscopy (LIBS) and UV-Vis-IR Hyperspectral Sensing. LIBS is a plasma based spectroscopic method where the sample surface is irradiated by high power laser. The light emitted from the plasma contains atomic -molecular spectral information and can be detected using a simple CCD based spectrometer. UV-Vis-IR Hyperspectral Sensing is produced by the reflection of light from the sample’s rough surface in all directions and it can be collected by using an ellipsoid or paraboloid mirror arrangement. The electromagnetic radiation emitted by the samples in the UV-Vis, NIR and MIR region can be used for molecular characterization. The spectrometer splits different wavelengths through a CCD arrangement in 2D spatial and spectral dimensions, thus a hyperspectral cube of data is generated. Chemometric techniques such as principal component analysis (PCA), K- nearest neighbors (KNN), support vector machine (SVM) among others, can be applied to LIBS and Hyperspectral data for better classification and quantification purposes in copper ores. Real- time determination of elemental and mineral species used for online processing control will help to achieve the copper industry 4.0. INTRODUCTION The demand for copper mineral resources is intensely growing with the increase in population, per capita GDP, the development of new technologies and the increase in global living standard. With the rise in consumption of copper, it is important to optimize mining and metallurgical processes tending to the copper industry 4.0 (Ge, Song, Ding, & Huang, 2017). The real-time analytical assessment in the mining and metallurgical processes is a crucial part for allowing the global improvement in mining industry. The features considered for better analytical assessment are the instrumental automation and interconnection, real time results, low cost, quality in terms of accuracy and precision. Furthermore, improving recovery (extraction), timing and quality of final products avoiding environmental impacts. Some elements such as Cu, Fe, Ag, Au, Mo, S, As, Pb, Zn are important to be determined in the process control. Additionally, rapid mineral identification of few species such as CuFeS2, Cu4FeS5, FeS2, CuS, Cu2S, MoS2, Cu3AsS4, FeAsS, among other can be challenging.

Jan 1, 2019