High-temperature sedimentation

High-temperature sedimentation characteristics. Slurry settling rates at temperatures in excess of 100 C have been obtained in quartz tube 8 mm in diameter [54]. These data, obtained with a slurry of thorium oxide prepared by a 650°C calcination of thorium formate [55], indicated that the slurry was already in the compaction zone of settling above 500 g Th/kg H2O at 200 to 300°C. At a concentration of 1000 g Th/kg H2O, no settling occurred at temperatures above 100°C. The small diameter of the tube probably affected the concentration at which the slurry went into compaction. 

The effect of thorium sulfate additions on the high-temperature sedimentation properties of a thoria slurry (250 g Th/kg H2O) composed of spherical agglomerates approximately 15 microns in average size is shown in... 

Other properties of interest are carbon residue, sediment, and acidity or neutralization number. These measure respectively the tendency of a fuel to foul combustors with soot deposits, to foul filters with dirt and rust, and to corrode metal equipment. Cetane number measures the ability of a fuel to ignite spontaneously under high temperature and pressure, and it only applies to fuel used in Diesel engines. Typical properties ol fuels in the kerosene boiling range are given in Table 1. 

Barite and sphalerite tend to precipitate at lower temperature from the hydrothermal solution mixed with a large amount of cold seawater (but mixing ratio (seawater/hydrothermal solution) may be less than 0.2). These minerals precipitate on the seafloor and/or at very shallow subsurface environment. However, chalcopyrite tends to precipitate from high temperature solutions in ore bodies and/or at the sub-seafloor sediments. Usually shale which is relatively impermeable overlies the Besshi-type ore bodies. This suggests that hydrothermal solution could not issue from the seafloor and... 

V. A. Gorodilov, V. N. Shevchenko, S. I. Tipikin, A. D. Makurov, G. A. Makeev, and V. F. Fomichev. Method for high temperature seam oil deposit development— by pumping aluminium chloride and tri-sodium phosphate as sediment forming material. Patent RU 2094599-C, 1997. 

The geological cycle sediments from deep regions of the Earth, which are subject to high pressure and high temperature, are brought back to the Earth s surface by geological dynamics. The metamorphic rock is more labile than the starting material and can be leached more easily, so that a cycle is set up in which new clay species are formed. 

Sediment-free, on-axis systems at tectonic spreading centres, which have high temperature gradients (as they lie directly above magma chambers). The mean temperature of the ejected water is 620-640 K, the throughput 24 km3/year. 

An alternative method for the determination of particulate organic carbon in marine sediments is based on oxidation with potassium persulfate followed by measurement of carbon dioxide by a Carlo Erba non-dispersive infrared analyser [152,153]. This procedure has been applied to estuarine and high-carbonate oceanic sediments, and results compared with those obtained by a high-temperature combustion method. 

Aspila et al. [60] have described a semi-automated method for the determination of inorganic, organic and total phosphorus in river and lake sediments. Total phosphorus is extracted from sediments with 1M hydrochloric acid after ignition at a high temperature (550°C) (method 1) or by digestion with sulphuric acid-potassium persulphate at 135°C in a sealed PTFE-lined Parr bomb (method 2). 

Figure 2.1.1 shows the most common derivatisation methods for anionic surfactants reported in the literature [1]. The first method of LAS determination by GC consisted of a microdesulfonation procedure in which LASs were desulfonated in boiling phosphoric acid at high temperature [2-4] and the corresponding alkylbenzenes analysed. The microdesulfonation method was further improved by introducing additional concentration and clean-up steps [5—11], which allowed the determination of LAS in influent, effluent and river water samples at low qg L-1 levels [7,8] and sediment and sludge samples [8] at pg g-1. In addition to the desulfonation procedure, several derivatisation techniques have been used to make LAS analysis amenable to GC. 

All of the experimental evidence shows extraction of Li from hasalt, altered hasalt and sediments even at temperatures <100°C. Lithium was incorporated into clays at temperatures up to 150°C during hasalt alteration (Seyfried et al. 1984 James et al. 2003), with affinity proportional to the fluid/rock ratio, such that Li was simultaneously added to and removed from fluids. Under high temperature, solid-dominated hydrothermal conditions (c. 350°C), Li was universally removed from materials and kept in solution, rather than in alteration minerals. The limited isotopic fractionation at these conditions has been estimated as a 0.994 (= (fl.i/ Li,ecomiMynm imk)/( LiALis tai )) Chan et al. 1993 Seyfried et al. 1998). 

You et al. (1995) studied bulk samples of fluids incorporated in sediments from ODP Site 808, in the Nankai Trough, southwest of Japan. Pore fluids have somewhat variable isotopic compositions (8 Li = +10 to +21), with a spike of light compositions near the basal decollement. These authors interpreted the decollement zone geochemical anomaly to represent influx of waters with Li derived from leaching of sediments at high temperatures. 

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