Hot water extraction process

Fifty years have elapsed since the first major surge occurred in the development of the Athabasca oil sands. The main effort has been devoted to the development of the hot water extraction process 13 significant projects utilizing this process are reviewed in this paper. However, many other techniques have also been extensively tested. These are classified into several basic concepts, and the mechanism underlying each is briefly described. A critical review of K. A. Claries theories concerning the flotation of bitumen is presented, and his theories are updated to accommodate the different mechanisms of the primary and secondary oil recovery processes. The relative merits of the mining and in situ approaches are discussed, and an estimate is made of the probable extent of the oil sand development toward the end of this century. 

Fig. 2 illustrates the mass balance for the hot water extraction process treating... 

Schramm, L.L. and Smith, R.G. (1990) Monitoring electrophoretic mobility of bitumen in hot water extraction process plant water to maximize primary froth recovery. Canadian Patent 1,265,463,... 

Athabasca oil sand is a complex, variable mixture of sand particles, clays, bitumen and water (1). Currently, there exist two commercial operations to extract the bitumen from this matrix and upgrade it to synthetic crude oil, a partially refined product. Both operations use the hot water extraction process (2) on surface mined material. 

Isotherms were plotted therefore for the adsorption of tannin (tannic acid) at 25°C from aqueous solution to these clays, at pH 4, before and after electrostatic adsorption of ferric ions. The results (Figures 10,11) indicate unequivocally that the presence of ferric ions, adsorbed to the clays in an ion-exchange sense, increases the adsorption significantly. This is a result most likely of a chelation effect. At pH 8.5, meaningful adsorption data could not be obtained, presumably because ferric iron is hydrolyzed at this pH and would not be immediately available for chelate formation. This implies that any chelation-promoted adsorption present in the clay slimes must have taken place prior to the industrial hot water extraction process. 

Figure 38. Results of a battery of bioassays (acute and chronic) conducted on extraction tailings water from Syncrudes hot water extraction process that was allowed to age naturally (isolated from fresh tailings input for 7 years). Initial LC50 to rainbow trout was < 10%. (Note the higher the percentage, the lower the toxic response.)...

Molten polycaprolactam, at the end of equilibrium polymerization, contains 10 - 12 % low molecular-weight material consisting of unreacted monomer and of cyclic oligomers. For most end-uses, this low m.w. portion has to be removed. For this purpose, Hopff and Ufer developed a hot-water extraction process for nylon 6 chips [25], As an alternative process, vacuum demonomerization of the polymer melt in the autoclave was practiced as early as 1939/1943 [26], Hot-water leaching and vacuum extraction were further elaborated and incorporated in integrated, continuous processes for the manufacture of nylon 6 polymer (Fig. 5). In the case of vacuum extraction the integration may also include fiber manufacture by direct spinning [26]. 

Agar is a gelatinous product isolated from seaweed (red algae class, Rhodophyceae), e. g., Ge-lidium spp., Pterocladia spp, and Gracilaria spp., by a hot water extraction process. Purification is possible by congealing the gel. 

In liquid-solid extraction (LSE) the analyte is extracted from the solid by a liquid, which is separated by filtration. Numerous extraction processes, representing various types and levels of energy, have been described steam distillation, simultaneous steam distillation-solvent extraction (SDE), passive hot solvent extraction, forced-flow leaching, (automated) Soxh-let extraction, shake-flask method, mechanically agitated reflux extraction, ultrasound-assisted extraction, y -ray-assisted extraction, microwave-assisted extraction (MAE), microwave-enhanced extraction (Soxwave ), microwave-assisted process (MAP ), gas-phase MAE, enhanced fluidity extraction, hot (subcritical) water extraction, supercritical fluid extraction (SFE), supercritical assisted liquid extraction, pressurised hot water extraction, enhanced solvent extraction (ESE ), solu-tion/precipitation, etc. The most successful systems are described in Sections 3.3.3-3.4.6. Other, less frequently... 

Soybeans have been used as food in the Orient since ancient times and various methods have been developed to make soybeans as palatable as possible. In recent years, a large number of these simply processed soyfoods are emerging in the West. Tofu and tempeh are the most popular and have the fastest growth rate of any soyfood in America. Tofu is made by coagulating the protein with a calcium or magnesium salt from a hot-water extracted, protein-oil emulsion of whole soybeans. 

There are several potential sources of error in these methods. The filters routinely used have a relatively high and somewhat variable sulfate content, so that, at concentrations lower than 10 Mg/m and sampling periods less than 24 h, the reliability of tlie sulfate measurement is reduc. Several different types of filtering media adsorb sulfur dioxide during the ftrst few hours of sampling this alters the amount of sulfate observed. This interference can become critical when sampling periods are less than 24 h and the concentration ratio of sulfur dioxide to sulfate is greater than 5 1. Interference can also be introduced by hot-water extraction when reduced sulfur compounds like sulfite are present, because they are oxidized to sulfates in this process. Another possible error source is that some of the various analytic procedures us for sulfate determination may be influenced by other substances also present in the particulate matter. 

Eskilsson, C.S., K. Hartonen, L. Mathiasson, et al. 2003. Pressurized hot water extraction of insecticides from process dust—comparison with supercritical fluid extraction. J. Sep. Sci. 27 59-64. 

Both of the Canadian plants use the technique of hot water extraction to remove the bitumen from the tar sand. In this procedure the tar sand, steam, sodium hydroxide, and hot water are mixed and tumbled at a temperature of around 90°C. Layers of sand pull apart from the bitumen in this process. Additional hot water is added and the bitumen-sand mixture is separated into two fractions by gravity separation in cells in which the bitumen rises to the top and is skimmed off, while the sand settles to the bottom. The upgrading of the bitumen to a synthetic crude is then accomplished by oil refinery procedures including coking, in which carbon is removed by thermal distillation and hydrotreating. 

Figure 15. Plot of oil recoveries versus process aid addition level from the hot water flotation processing of an oil sand in a continuous pilot plant. Also shown is the correspondence with the zeta potentials, measured on-line, of emulsified bitumen droplets in the extraction solution. (Plotted from data in reference 50.)...

The process of extraction of oil with hot water was originally designed by K. A. Clarke and called the hot-water washing process for exploitation of Arthabasca bituminous tar sand [1, 2, 3 ]. The term hot water is used instead of steam or water vapor , because tbe operating temperature (around 90 °C) was maintained near tha water boiling point without ever reaching it [ 4 ]. 

In the USA, most type A gelatin is obtained from pig skins. This material is washed in cold water for a few hours to remove extraneous matter and is then digested in dilute mineral acid (HGl, H2SO4, H2SO3, or H3PO4) at pH 1-3 and 15-20°C until maximum swelling has occurred. This process takes approximately 24 hours. The swollen stock is then washed with water to remove excess acid, and the pH is adjusted to pH 3.5—4.0 for the conversion to gelatin by hot-water extraction. 

Sulfur gases arising during synthetic crude production from the bitumen and from the high-pressure hydrogenation process for synthetic crude stabilization are captured in amine scrubbers, and subsequently converted to sulfur via the Claus process (Chap. 9). Approximately 1500 tonnes of sulfur are produced daily from these sources by the two older hot water extraction plants. Occasionally these control measures have been inadequate to maintain low ambient air sulfur dioxide concentrations, particularly during an inversion episode. The potential of vanadium and nickel recovery from fly ash, which is possible on the scale of 1,600 and 3,900 tonnes/year, respectively, has also been considered. 

Of the Canadian deposits, the largest, Athabasca, is at least 4 times the size of the largest conventional oil field, Ghawar, in Saudi Arabia (5). Of the Athabasca s estimated 600 billion barrels of bitumen, about 60 billion barrels could be recovered by surface mining of the oil sand followed by beneficiation to separate the oil. Currently two commercial plants are producing synthetic crude oil from the Athabasca deposit. In these operations, the oil sands are first mined, and the bitumen is extracted by a hot-water flotation process, which produces a bituminous froth. After breaking the froth, the separated bitumen is subsequently upgraded by refineiy-type processes to produce synthetic crude oil. In order to understand the nature of the froths produced, the nature of oil-sand structure will be reviewed first, and then the flotation process from which froths are produced will be examined. 

The main sources of inorganic ions found in tailings water are (1) oil sand connate water (water in the spaces between the sand grains), (2) makeup water taken from the Athabasca River for use in plant processes, and (3) chemicals added during hot water extraction and other processes. These sources contribute ions that accumulate in the pond water that is recycled to oil sands processing. 

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