bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trajectory planning for grade transitions: A restricted form approach
Authors: Gilbert W. A. M. , Lipsett M. G. , Forbes J. F. 
Published: May 2010

AbstractTrajectory planning is of importance for controlling chemical processes under transient conditions. Many of the available techniques for trajectory optimization yield solutions that cannot be implemented. Furthermore, many transient processes are operated manually, which further reduces the classes of trajectories that may be used. In this article, input trajectories are restricted to step/ramp functions, which are easily implemented by manual control or simple control schemes. Direct transcription of the dynamic optimization problem was used to allow the solution to be found using algebraic optimization techniques. The proposed method serves as a useful control policy evaluation tool, where comparison of unrestricted and restricted trajectories gives insights into the gains associated with adopting a more sophisticated control scheme. The restricted inputs approach is applied to several benchmark problems, including gravity separation in an oilsands process.
Kinetics of non‐isothermal decomposition of basic cobalt carbonate
Authors: Liu Bingguo , Peng Jinhui , Zhang Libo , Li Wei , Zhou Liexing 
Published: May 2010

AbstractThe kinetics of the thermal decomposition of basic cobalt carbonate was investigated under non‐isothermal heating in air media using thermogravimetric analysis (TGA). TG‐DTG curves showed that the decomposition proceeded through two well‐fined steps in air. Weight loss of the thermal decomposition of basic cobalt carbonate was in good agreement with the theoretical weight loss. The isoconversional method has been applied to the data in order to evaluate a dependence of the effective activation energy on the extent of conversion, and the possible conversion functions have been estimated through the multiple linear regression method. The average apparent activation energies of the second steps (0.4 ≤ α ≤0.9) were 96.607–144.537 kJ/mol.
Effect of natural surfactants released from athabasca oil sands on air holdup in a water column
Authors: Zhou Zhiang , Xu Zhenghe , Masliyah Jacob 
Published: May 2010

AbstractNatural surfactants released from Athabasca oil sands are a crucial component in water‐based bitumen extraction processes. The effect of natural surfactant released from estuarine and marine oil sands on air holdup was investigated using a water column. The air holdup in the resultant supernatant of the conditioned oil sands slurry was found to be much higher than that in de‐ionized water. A further increase in air holdup was observed with the supernatant obtained from the oil sands slurry conditioned with caustic. Aging of the ore prior to bitumen extraction caused an increase in air holdup. The presence of small amount of fine solids in the supernatant resulted in a higher air holdup for all the cases studied. The present study shows that the higher air holdup and poorer processibility of marine ores, compared with estuarine ores, could be accounted for by the release of larger amount of surface active species and the presence of more fine clays in the ores.
Factors affecting the aeration of small bitumen droplets
Authors: Moran Kevin , Masliyah Jacob , Yeung Anthony 
Published: May 2010

AbstractSmall bitumen droplets, roughly 10 to 40 μm in diameter, constitute a significant fraction of the total hydrocarbon in an oil sands flotation process. In this study, the aeration of such droplets is examined—both from a surface energetic perspective as well as from direct observations. The spreading coefficient associated with bitumen aeration is evaluated based on in situ measurements of interracial and surface tensions. In addition, micropipette techniques are employed to monitor the aeration process and to quantify the probability of aeration. Our results suggest that a positive spreading coefficient does not always guarantee the aeration of bitumen droplets, and that such a process may best be described from a statistical stand point.
Novel reactor for cyanide solution treatment
Authors: Fortin Luc , Kasireddy Vijaya K. , Soucy Gervais , Bernier Jean‐Luc 
Published: May 2010

AbstractThis paper presents the treatment of cyanide solution being derived from the aluminum industry by direct contact with thermal plasma in a novel reactor. The energy is provided by a plasma submerged in the solution which allows direct contact between the plasma and the solution. The scope of this study was to determine the feasibility of treating free and complex cyanides in solution through bench‐scale operations. An innovative reactor was designed and fabricated to provide stable operating conditions. Many parameters were studied, such as the NaOH concentration (32 and 57 g/L), initial SPL (Spent PotLining) leachate concentration (154 and 354 mg/L), plasma power (10 and 19 kW) and relative reactor pressure (0 and 1.34 MPa). These experiments allowed us to evaluate the kinetics of complex cyanide decomposition under thermal plasma conditions. At atmospheric pressure (about 100°C), the rate of cyanide decomposition was 12 times greater than that of thermal hydrolysis occurring in a plug flow reactor at the same temperature. These improvements are attributed to the presence of both steep thermal gradients and reaction photocatalysis by the plasma UV radiation.
Effect of clays and calcium ions on bitumen extraction from athabasca oil sands using flotation
Authors: Kasongo Tshitende , Zhou Zhiang , Xu Zhenghe , Masliyah Jacob 
Published: May 2010

AbstractA novel approach, based on the doping of rich estuarine oil sands with calcium and/or clays, was developed to study bitumen extraction. The batch flotation tests showed that the addition of either calcium ions up to 40 p.p.m., or kaolinite, illite and montmorillonite clays at 1 wt% of oil sands processed had marginal effect on bitumen recovery from the estuarine ores. A sharp reduction in bitumen recovery was observed only when calcium ions greater than 30 p.p.m. and 1 wt% montmorillonite clays were added together. While bitumen recovery correlated well with changes in water/air/bitumen contact angle, no correlation was found between bitumen recovery and measured zeta potential of clays or surface tension of the supernatants from the flotation slurry. The wettability of bitumen was identified as a key element in determining bitumen recovery. The aqueous solution analysis for calcium ions showed that most of the added calcium ions disappeared from the solution when montmorillonite clays were present. The addition of illite or kaolinite clays changed the calcium ion concentration in the slurry only marginally. Stronger adsorption of calcium ions on montmorillonite than on either kaolinite or illite is considered to be responsible for the increased bitumen wettability, and hence reduced bitumen recovery.
Aqueous sulphur dioxide leaching of Cu, Ni, Co, Zn and Fe from smelter slag in absence of oxygen
Authors: Ahmed Isaac B. , Gbor Philip K. , Jia Charles Q. 
Published: May 2010

AbstractSmelter slag and sulphur dioxide are waste products of non‐ferrous pyrometallurgical processes. Dissolution behaviour of Co, Cu, Fe, Ni and Zn from smelter slag in aqueous sulphur dioxide was studied. Experiments were carried out in batch mode, under near ambient conditions. Under the conditions studied, 81% Co, 60% Fe, 35% Ni and 68% Zn extraction were achieved within 3 h, while Cu behaved very differently. The initial dissolution of Cu was rapid, but subsequent precipitation lowered its overall extraction. The precipitation of Cu was more temperature sensitive than its dissolution. At 65°C all the dissolved Cu was precipitated in 2.5 h. The successive precipitation was explained based on the solution chemistry of the Cu‐Fe‐S(IV) system. Dissolution kinetics of the other metals were evaluated using the shrinking core model. Diffusion through the product/ash layer appeared to be the rate controlling step. SEM‐EDS analysis was used to characterize the slag and to confirm the existence of a product/ash layer after leaching.
The effect of particle shape on pipeline friction for newtonian slurries of fine particles
Authors: Schaan Jason , Sumner Robert J. , Gillies Randall G. , Shook Clifton A. 
Published: May 2010

AbstractExperiments have been conducted to assess the effect of particle shape on pipeline friction in turbulent flow, using laboratory pipelines of nominal diameter 50 mm and 150 mm. The experiments were intended to examine the extent to which a fluid model is appropriate for slurries of this type, especially at high solids concentrations. The experiments confirm that fluid friction at low and moderate solids concentrations is proportional to slurry density, with particle shape being of minor importance. At high solids concentrations, additional increases in friction are observed and these depend upon the ratio of the solids concentration to the maximum settled concentration. Although this friction increase is qualitatively similar to that which would result from increased slurry viscosity, the evidence suggests that particle‐wall contact is the mechanism. However, the transition from turbulent to laminar flow indicates that an effective viscosity should be used in calculating critical Reynolds numbers.
Anomalous friction in slurry flows
Authors: Schaan Jason , Shook Clifton A. 
Published: May 2010

AbstractExperiments conducted with water slurries of 1 mm particles of specific gravity 1.59 in a laboratory pipeline 0.105 m in diameter have provided evidence of a change in the friction mechanism at velocities above 3 m/s. These flows were stratified and at low velocities the frictional pressure gradients were in satisfactory agreement with the predictions of the conventional two‐layer model. However at higher velocities the friction is substantially lower than predicted. Measurements of concentration and velocity distributions within the pipe show that no major change in flow regime occurs concurrently with the change in the friction mechanism. It appears that the effect is due to a change in the nature of the particle‐wall interaction, of a type which suggests that an inward‐acting force affects the particles adjacent to the wall.
Bitumen effects on pipeline hydraulics during oil sand hydrotransport
Authors: Sanders R. Sean , Ferre Alan L. , Maciejewski Waldemar B. , Gillies Randall G. , Shook Clifton A. 
Published: May 2010

AbstractOil sand hydrotransport technology has become increasingly important to Syncrude Canada Ltd. and the oil sands industry. Oil sand slurries are complex, multiphase mixtures of bitumen, coarse solids, fine solids, water and air that can exhibit time‐dependent behaviour, wherein pipeline friction losses increase drastically with time. Four separate experimental programs were conducted to study the effect of bitumen on pipeline hydraulics using 100 mm and 250 mm (I.D.) recirculating and once‐through pipeline loops. The results show that pipeline friction losses increase as a bitumen coating forms on the pipe wall. The effect is more pronounced at 50°C, but also occurs at lower temperatures.
The effect of sand‐clay slurries on the performance of centrifugal pumps
Authors: Sellgren Anders , Addie Graeme , Scott Stephen 
Published: May 2010

AbstractThe addition of clay to sand slurries has been found to reduce the pipeline friction losses, thus lowering the pumping head and power consumption. Pump water heads and efficiencies are decreased by the presence of solid particles. Experimental results are presented for a centrifugal pump with an impeller diameter of 0.625 m for three narrowly graded sands with average particle sizes of 0.64, 1.27, and 2.2 mm. Reductions in head and efficiency of up to 30% were observed for sand slurries with volume concentrations of up to 35%. Head and efficiency were lowered by about one‐third for sand‐clay mixtures with sand to clay mass ratios between 4:1 and 6:1. Comparisons are made with design criteria and a mechanistic model approach based on a prediction of the relative motion of the solids and water in the volute region of the pump.
An integrated approach for coal tailings management
Authors: Choung Jaewon , Xu Zhenghe , Szymanski Jozef 
Published: May 2010

AbstractA detailed study on an integrated process featuring three distinct mechanisms (i.e., hydrophobic extraction, coagulation and flocculation) is presented. In this process, fine coals in the tailings stream are extracted into a mineral oil by hydrophobic extraction, while coagulant and flocculant are used to aid effluent clarification by coagulation/flocculation. With a single stage process, a coal‐in‐oil mixture is produced as a potential fuel, while clarifying the water for recycling. The hydrophobicity of coal is found to be a key parameter in coal extraction. The addition of mineral oil prior to flocculant and coagulant, especially in the presence of fine clays, is beneficial for recovering weakly hydrophobic fine coals. Fine clays are found to stabilize coal‐rich oil droplets, reducing coal recovery. The presence of hydrophobic coal enhances droplet coalescence and improves process performance. In a case study using a tailings stream from OBED coal preparation plant, it was found that re‐grinding of original tailings is necessary to expose fresh hydrophobic surfaces. Applying this single stage unit operation to a tailings containing 52% ash, a combustible recovery greater than 85% in the form of coal‐in‐oil mixture at product ash content less than 14 wt% was achieved.
Determining equivalent pore diameter for rigid porous spargers
Authors: Gomez Cesar O. , Escudero Ramiro , Finch James A. 
Published: May 2010

AbstractPrediction of the properties of gas dispersions (e.g., bubble size) generated by porous spargers requires a knowledge of the pore diameter. Three methodologies for determination of an equivalent pore diameter De of a rigid SS sparger of the type used in column flotation have been developed. In the first, De is determined by fitting the bubble diameter predicted by the Kumar/Kuloor model to that measured. In the second, an estimation of bubble diameter is substituted. Estimation was tested using drift flux analysis and Molerus' uniform bubbling model: the former gave acceptable agreement with the measured. Fitting to the estimated bubble diameter offers a simplification over using the measured bubble diameter. The third approach was a further simplification. By combining the Kumar/Kuloor model with drift flux analysis, De is estimated by fitting predicted to measured gas holdup. The methodologies are evaluated on a set of SS spargers using water with a flotation frother, Dowforth 250C. All three methodologies give similiar estimates of De.
Une nouvelle technologie d'appareils de dépôt chimique en phase vapeur. Partie 2 : Modélisation du dépôt de silicium pur à partir de silane et de silicium dopé in situ au phosphore
Authors: Vergnes Huges , Duverneuil Patrick , Couderc Jean‐Pierre 
Published: May 2010

AbstractLa modélisation des réacteurs de CVD permet, d'abord, une meilleure compréhension des mécanismes conduisant au dépôt et constitue, ensuite, un outil très performant pour assister la conception d'appareils industriels et l'optimisation de leurs conditions d'utilisation. Elle autorise une recherche plus sure et plus rationnelle des variables opératoires permettant l'élaboration de dépôts conformes aux spécifications requises. La mise en équation est effectuée, ici, dans le cas du dépôt de silicium polycristallin à partir de silane pour une technologie nouvelle d'appareil de LPCVD. Les hypothèses et méthodes nécessaires à l'elaboration des logiciels de modélisation sont énoncées et discutées, avant la présentation des résultats et leur confrontation avec les données de l'expérience. Cette étude est finalement étendue au cas, plus complexe, des dépôts dopés in situ au phosphore.
A two‐phase model for variable‐density fluidized bed reactors with generalized nonlinear kinetics
Authors: Tafreshi Zahra M. , Opoku‐Gyamfi Kingsley , Adesina Adesoji A. 
Published: May 2010

AbstractA model based on the classical two‐phase concept is developed for the simulation of variable‐density reaction with generalized nonlinear kinetics in a bubbling fluidized bed. The influence of reaction density parameter on the fluidodynamics and performance of the reactor for four general types of reactions was explored. The results show that the expansion factor has a significant effect on both fluidodynamic characteristics and reaction conversion. In all types of reactions, higher values of hydro‐dynamic variables were obtained when ϵ ≥ 0. Reaction conversion, however, dropped as the expansion factor increased. This trend was more pronounced for reaction orders higher than unity. This suggests that bubbling fluidized operations are probably not optimal and applicable for certain types of reactions. Comparative analysis between reaction type and implications for optimum fluidized bed reactor are discussed.
Mechanism of the ClO2 generation from the H2O2‐HClO3 reaction
Authors: Yin Guohong , Ni Yonghao 
Published: May 2010

AbstractThe development of chlorine containing species during the hydrogen peroxide‐based chlorine dioxide generation process has been determined. Accordingly, two distinct phases, namely the induction period and the steady‐state phase, were identified. In the induction period, it was observed that chloride and chlorous acid are generated, while chlorine, a byproduct from some methanol‐based processes, is not detectable. The absence of chlorine is explained by the fast reaction kinetics between hydrogen peroxide and chlorine, which results in the formation of chloride. In the steady‐state phase, due to the accumulation of chloride and chlorous acid during the induction period, the reaction between chloric acid and chlorous acid, which is responsible for the generation of chlorine dioxide in the hydrogen peroxide‐based ClO2 process, becomes possible. Chloride is a catalyst in such a reaction.
Analysis of gamma‐ray imaging data to describe hydrodynamic properties of gas–polyethylene fluidized beds
Authors: Zarabi Taghi , Kantzas Apostolos 
Published: May 2010

AbstractA scintillation gamma camera was used for measuring the instantaneous velocity profile and average velocity as well as the trajectories of a radioactive particle in small laboratory scale air–polyethylene–fluidized beds. A large number of frames, with frequencies between 1 and 50 Hz, were analyzed to investigate the effects of bed height, gas velocity and particle morphology. Subsequently: (1) horizontal and axial variations of the particle velocity were found; (2) three different flow zones along the axis (i.e., entrance zone, circulation zone and free board) were quantified; and (3) a characteristic time and a new definition of circulation (cycle) period were introduced. It was also found that the particle sometimes oscillates in the free board or gets trapped in the entrance zone.
Continuous protein recovery using a liquid–solid circulating fluidized bed ion exchange system: Modelling and experimental studies
Authors: Lan Qingdao , Zhu Jing‐Xu (Jesse) , Bassi Amarjeet S. , Margaritis Argyrios , Zheng Ying , Rowe Gerald E. 
Published: May 2010

AbstractIn this study, a continuous protein recovery process using a Liquid–Solid Circulating Fluidized Bed (LSCFB) ion exchange system is described and a model with known kinetics has been developed. Experiments and computer simulations using Matlab™ are conducted at different operating conditions. The effects of hydro‐dynamic parameters and kinetic parameters on the performance of the LSCFB ion exchange system are discussed. The model is shown to be applicable for the design of LSCFB ion exchange systems for protein recovery.
Formation of drops at narrow slots in a centrifugal liquid–liquid contactor
Authors: Wadley Robert , Lee Jonathan G.M. , Wraith Albert E. 
Published: May 2010

AbstractIn experiments on the dispersion of organic phases into aqueous phases, drops were generated continuously at narrow slots of width 12 μm ≤ w ≤ 125 μm mounted peripherally and normal to the radius in a ‘Hi‐Gee’ centrifugal contactor. The drops formed at an array of sources attributed to the Rayleigh‐Taylor instability distributed an average distance
equation image
apart where σ is the interfacial tension of the phases, Δρ their density difference and g the applied centrifugal acceleration. Measured Sauter mean drop diameters were in the range 0.48 to 1.00 mm. The average drop size, d, was given by
equation image
where d̄* = 0.1538 ± 0.0016 m1/3 is a measured capillary factor. Drop size was marginally affected by inertial forces at the highest flow rates.
Adsorption of flavour esters on granular activated carbon
Authors: Ismadji Suryadi , Bhatia Suresh K. 
Published: May 2010

AbstractThis article reports on the liquid phase adsorption of flavour esters onto granular activated carbon. Ethyl propionate, ethyl butyrate, and ethyl isovalerate were used as adsorbates, and Filtrasorb 400 activated carbon was chosen as the adsorbent. Sips, Toth, Unilan, and Dubinin‐Radushkevich isotherm equations which are generally used for heterogeneous adsorbents were used to fit the data. Although satisfactory in fitting the data, inconsistency in parameter values indicated these models to be inadequate. On the other hand the Dubinin‐Radushkevich model gave more consistent and meaningful parameter values and adsorption capacities. By employing the Dubinin‐Radushkevich equation, the limiting volume of the adsorbed space, which equals the accessible micropore volume, was determined, and found to correlate with the value from carbon dioxide adsorption.
Selectivity engineering in the O‐ versus C‐alkylation of p‐cresol with cyclohexene over sulfated zirconia
Authors: Yadav Ganapati D. , Ramesh Pala 
Published: May 2010

AbstractSolid acids are more widely used as heterogeneous catalysts, because they are eco‐friendly. This paper reports the results for the Friedel‐Crafts alkylation of p‐cresol with cyclohexene using solid acids sulfated zirconia, 20% w/w dodecatungstophosphoric acid (DTP) supported on K10 clay and ZnCl2/K10 (Clayzic). This reaction gave substantial amount of 1‐cyclohexyloxy‐4‐methyl benzene (O‐alkylated product) and 4‐cyclo‐hexyl‐4‐methyl phenol (C‐alkylated product). Both products are of commercial importance as perfume and insecticide respectively. Sulfated zirconia catalyst was shown to be better than others studied in terms of activity and selectivity to the O‐alkylated product. The kinetics were studied with sulfated zirconia as catalyst where the rate determining step was the surface reaction between chemisorbed cyclohexene and p‐cresol from the liquid phase within pores according to the Eley‐Rideal mechanism. The production of O‐alkylated p‐cresol is favoured at lower temperatures and C‐alkylated product at higher temperatures. The best operating temperature is 353 K. The activation energies for O‐ and C‐alkylation are 72.68 and 118.28 kj/mol, respectively.
Decarboxylation of rosin acids in fusion synthesis of Ca‐resinates—Thermogravimetric studies
Authors: Sundqvist Satu , Turunen Sari , Paatero Erkki 
Published: May 2010

AbstractFusion synthesis of Ca‐resinates was studied in a laboratory reactor and in a thermobalance. In the syntheses, the resination reaction takes place at 235°C and it is followed by the thermal decarboxylation of rosin acids at 265°C. The kinetics of the thermal decarboxylation was modelled in the synthesis reactor using calcium contents corresponding to the theoretical target acid values 50 to 90 mg(KOH)/g. In the thermobalance, the kinetics of the decarboxylation reaction could be continuously followed and accurate kinetic results were thus obtained in different reaction conditions. The oxidative and thermal decarboxylation were separately studied in the thermobalance at the reaction temperature range of 245°C to 275°C and in different atmospheres (air, N2, CO2) at 260°C. The oxidative decarboxylation was observed to be faster than the thermal decarboxylation during the first 2 h. After that, however, the oxidative decarboxylation was restricted by the apparent reaction equilibrium.