Proper conditioning of an oil sand/water slurry is essential for the efficient extraction of bitumen. The conditioning process depends on such variables as ore grade, temperature, mixing intensity, mixing time, and water composition. A technique has been developed in which a microscope and video cameras are used to observe a slurry stirred in a glass cell to evaluate, on a comparative basis, the effect of conditioning parameters on bitumen recovery. Several ores and their blends were studied and found to exhibit large differences in their conditioning behaviour. The method offers the capability of diagnosing ore processability problems and optimizing slurry conditioning. 相似文献
Mullite-type phases with about 74 wt% Al2O3 and 26 wt% SiO2 were prepared from tetraethyl orthosilicate and aluminum butylate between 950° and 1000°C. The lack of 120/210, 240/420, 041/401, and 250/520 reflection pair splitting on the X-ray diffractograms indicates tetragonal symmetry, whereas normal mullite is orthorhombic. We believe that the tetragonal character of the phase is due to twinning and/or domain formation of orthorhombic structural units in an elementary cell scale. Therefore, the mullite-type phase should be designated as pseudotetragonal rather than tetragonal. According to our present knowledge, pseudotetragonal mullite is formed from highly reactive metal organic compounds only. The phase is metastable and transforms gradually to orthorhombic mullite at temperatures above 1000°C. 相似文献
The usefulness of 3,5-dibromohexane-1,4-diol, 3,5-dichloroheptane-1,4-diol, 3,5-dibromoheptane-1,4-diol, 2-(4,5-dichlorophentyl)propane-1,3-diol and 2-(4,5-dibromopentyl)propane-1,3-diol for the synthesis of rigid polyurethane foams with reduced combustibility was investigated. In addition possibility of utilization of hexane-1,4-diol, heptane-1,4-diol, 2-(pent-4-enyl)propane-1,3-diol and 6-hydroxymethylheptane-1,2,7-triol for the manufacture of foamed polyurethanes is examined too. 相似文献
Conditioning of an oil sand slurry is a critical step in the extraction of bitumen from oil sand ore. To model the conditioning process, a constant‐number Monte Carlo algorithm is used to simulate the mean‐field kinetics of coalescing bitumen drops and air bubbles. The coalescence rate of drops and bubbles is described by the model of Coulaloglou and Tavlarides (1977). Simulations yield results that are consistent with aerated bitumen drop sizes and conditioning times reported in the literature. The effects of turbulent energy, bitumen concentration, and initial bitumen drop size on the evolution of drop size distributions are investigated. 相似文献
Resistance to coking is one of the most important characteristics of nickel catalysts used for steam reforming of hydrocarbons, CO2 reforming or methanation of carbon oxides. Microbalance reactors have for a long time played an important role in catalyst deactivation studies, providing coking and coke gasification rates. However, conventional thermogravimetric microbalances have a number of limitations. The aim of this paper is to compare initial temperatures of coking of Ni and Ni-Mo catalysts (with different resistance to coking) obtained in the temperature-programmed reaction of n-butane with steam with the results of coking rates obtained by the traditional thermogravimetric method. The investigations showed great agreement of the results. 相似文献
The effect of Co content on the catalytic activity of CoSiBEA zeolites in the selective catalytic reduction (SCR) of NO with ethanol is investigated. The CoxSiBEA zeolites (x = 0.3, 0.7, 3.6 and 6.75 Co wt.%) are prepared by a two-step postsynthesis method which allows to control the introduction of cobalt into zeolite and thus to obtain catalysts with specific Co sites. The nature of the active sites is characterized by XRD, diffuse reflectance UV–vis, H2-TPR and XPS.
The catalytic activity of CoxSiBEA strongly depends on the nature and environment of Co species. Zeolites with isolated lattice tetrahedral Co(II) (Co0.3SiBEA and Co0.7SiBEA samples) are active in SCR of NO with ethanol with selectivity toward N2 exceeding 85% for NO conversion from 20 to 70%. When additional isolated extra-lattice octahedral Co(II) species appear (Co3.6SiBEA sample), the full oxidation of ethanol by dioxygen becomes a very important reaction pathway. In presence of additional cobalt oxides (Co6.75SiBEA sample), the activity and selectivity toward N2 substantially change and full oxidation of ethanol to CO2 is the main reaction pathway and full NO oxidation also takes place in the temperature range 550–775 K. The lack of correlation between the activity in SCR of NO with ethanol and NO oxidation to NO2 suggests that the two reactions are more competitive than sequential. 相似文献
A new method for the evalution of the quality of electropolished suraces is presented. A theoretical analysis was carried out and the results were confirmed by experiment. The relevance of the slope of the surface profile to the evaluation of surface quality was determined. Electropolishing processes affect to a much greater extent the reduction of the standard deviation of the slope than the reduction of the standard deviation ordinates. 相似文献
Construction on the first metro line in Warsaw began in 1983. The total length of the line will be 23 km, with an average distance between stations of 1 km. According to plans, the first 12 km of the line will be in service in 1990, and the total line will be completed in 1994. The line will run at relatively shallow depths, with an average of 9 m between track and ground level. The metro facilities will be constructed in Quarternary soil formations, mainly by the cut-and-cover method. The paper describes the development of the plans and gives detailed information about the design. 相似文献
The paper presents a review of the passive methods of sampling of inorganic and organic atmospheric pollutants. The importance of these methods, enabling both evaluation of workplace personal exposure and area monitoring, has been discussed. Commercially available personal monitors, as well as devices under further laboratory investigation have been described. Fundamental theoretical equations describing the operation of both passive devices based on diffusion through an air gap to a layer of collective media and passive devices with permeable membranes have been put forward. Presented and discussed herein are papers dealing with the investigation of the applicability of these devices under laboratory and field conditions, as well as with the comparison of passive monitors with active devices (e.g., detector tubes). 相似文献