Thermal illite

Abstract The aim of this work was to study the simultaneous effect of amount of clay, activation temperature, contact time, pH, and size of the adsorbent on the retention of oil-grease thermally activated illite by adsorption. The values obtained for the percentage of oil-grease removed ranged from 93.87% for 110°C up to 66.73% for 900°C. The adsorption experiment showed surface that the stronger heat treatment the most effective adsorption of oil-grease. 

Fig. 20.2 Effect of temperature on percentage adsorption of oil at natural and thermal activate illite clay minerals...

Table 20.3 Effect of particle size on adsorption of oil thermal activated illite mineral...

Adsorption of oil- grease for seven different particle sizes on thermally activated illite clay (>710 pm 710-600 pm 600-425 pm 425-355 pm 355-150 pm 150-75 pm <75 pm) was studied keeping the other parameters as constant. The result of variation of this particle sizes on oil-grease adsorption show in Table 20.3. 

Figure 20.5 shows the effect of contact time and percentage adsorption oil-grease on the removal by thermally activated illite. 

The adsorption capacity of thermal activated illite is increased as 5.5% according to natural illite mineral. It has seen that there is on significant loss of adsorption capacity of illite at about 550°C. The capacity of oil - grease adsorption is... 

Kozlowska, A. 2006. K-Ar dating of authigenic illite from sandstones and thermal history of the Lublin Carboniferous basin (SE Poland). Sediment 2006. Gotingen, Abstracts, 106. 

The size of the reactors is quite variable. In length, the biggest reactor has dimensions of 12 x 18 m and has a thickness of 20 to 50 cm (Fig. la). The core of the reactors consists of a 5 to 20 cm thick layer of uraninite embedded in clays (illite and chlorite). Clays around the reactors result from the hydrothermal alteration of the host sandstone during the fission reactions. This alteration occurred at a temperature close to 400 °C in the core. Temperature decreased drastically toward the vicinity with a thermal gradient of 100 °C/m (Pourcelot Gauthier-Lafaye 1999). The uranium content of the core ranges between 40 and 60%. Accessory minerals are mainly sulphides (pyrite and galena), hematite and phosphates (mainly hydroxyapatite). 

The AG between the assemblage of muscovite + chlorite at composition y and illite of this is likely to be relatively small and the tendency to recrystallize the muscovite from x to y compositions will be small at sedimentary conditions. However, as more thermal energy is added to the rock system, under conditions of deeper burial, the recrystallization will proceed more rapidly as temperature is increased. Evidence for such an effect can be found in Millot (1964) where sedimentary rocks coming from deeply buried or slightly metamorphosed series show the "chloritization" or kaolinitization" of detrital mica grains in splendid photographs. 

Pelitic rocks investigated in the same areas where corrensites are formed during alpine metamorphism (Kiibler, 1970) revealed the absence of both montmorillonite and kaolinite but the illite or mica fraction was well crystallized as evidenced by measurement of the "sharpness" of the (001) mica reflection (Kiibler, 1968). This observation places the upper thermal stability of the expandable and mixed layered trioctahedral mineral assemblages at least 50°C. above their dioctahedral correlevants. This is valid for rocks of decidedly basic compositions where no dioctahedral clay minerals are present. 

V is characterized by kaolinite-illite-chlorite assemblages beyond the stability of an expanding mixed layered potassic dioctahedral mineral and below the thermal stability of pyrophyllite. The establishment of such conditions will be difficult in that the non-appearance of a mineral is a poor diagnostic and, as we have seen, kaolinite is frequently eliminated from sediments before its upper stability limit in the presence... 

Mixed-layer clays, particularly illile-smeclite. are very common minerals and illustrate the transitional nature of the 2 1 layered silicates. The transition from smectite to illite occurs when smectite, in the presence of potassium front another mineral such as potassium feldspar, or from thermal fluids, is heated and/or buried. With increasing temperature smectite plus potassium is convened to illite. 

Radoslovich (1963b) has shown that when Na+ ions replace K+ ions in muscovite, the dimension of the b-axis is increased. This requires additional flattening and rotation of the silica and alumina tetrahedra. This suggests that the amount of Na+ that can be tolerated by the mica structure increases with temperature the increased thermal motions would allow the structure to accommodate local strains more readily. Thus, little Na+ would be expected in low-temperature illites. In addition, Na would leach out more readily than the K and any illite that had been through the weathering stage would not retain much of its Na. 

The most common type of mixed-layer clay is composed of expanded, waterbearing layers and contracted, non-water-bearing layers (i.e., illite-montmorillonite, chlorite-vermiculite, chloritc-montmorillonite). Most of these clays form by the partial leaching of K or Mg (OH)2 from between illite or chlorite layers and by the incomplete adsorption of K or Mg(OH)2 on montmorillonite- or vermiculite-like layers. They most commonly form during weathering or after burial but are frequently of hydro-thermal origin. 

The reactions of several other minerals which thermally decompose to form mullite have been studied by Si and Al NMR. These include the mica mineral muscovite, which also contained sufficient iron to permit a complementary Fe Mossbauer study (MacKenzie et al. 1987), the hydroxyfluoride mineral topaz (Day et al. 1995) and the semi-amorphous aluminosilicate minerals allophane (MacKenzie et al. 1991) and imogolite (MacKenzie et al. 1989). The same combination of NMR nuclei has been used to study the thermal decomposition of other aluminosilicates including an illite-rich clay (Roch et al. 1998), montmorillonite (Brown et al. 1987), and a related mineral, Fuller s Earth (Drachman et al. 1997). NMR has also been used to study the effect of water vapour on the thermal decomposition of montmorillonite clay compacts (Temuujin et al. 2000a). 

Smectite clay catalysts are potential alternative adsorbents, although some modifications of the natural mineral are necessary. Interlayer sites in smectite dehydrate at temperatures above 200°C, collapsing to an illitic structure. Since the ion-exchange capacity of smectite centres on the interlayer site, collapse must be prevented if clay catalysts are to be used in thermal treatments of chemical organic toxins. The intercalation of thermally stable cations, which act as molecular props or pillars, is one... 

The rate of the smectite - illite reaction is thus directly proportional to K"" and H+, but is retarded by and by dissolved silica and Na". In deepening sedimentary basins, the extent of the reaction at any depth also depends on the local thermal gradient (temperature) and the sediment burial rate (reaction time). Because smectites of small particle size are the least stable, they alter to illite at lower temperatures than do coarser-grained smectites (Fig. 9.5). 

Illite and montmorillonite are similar in structure and differ slightly from kaolinite in this regard. The first two are composed of two silicon-oxygen layers per octahedral layer containing iron, magnesium and aluminum and in kaolinite the ratio of tetrahedral and octahedral layers is 1. In clays thermal modification occurs at lower temperature than silica because the bonds formed between the Al, Fe, and Mg atoms and oxygen are weaker than the Si-0 bonds. 

Figure 4. SEM Photomicrographs Showing the Impact of Illite on the Thermal Behavior of Low Temperature Ash. Reproduced with permission from reference 19. Copyright 1984 VGB.

Sintered deposits form at the furnace exit at lower gas temperatures and in zones subject to rapid changes in direction. The deposit is composed of spheroidal particles, <40p, bound together by a molten substance. In those cases where substantial quantities of coarse pyrites are liberated from the pulverized coal, the spheroids are nearly pure FeaOa, as shown in Figure 11. The matrix contained silica, alumina, iron, and potassium, and has an initial deformation temperature of 1832°C, as determined by differential thermal analysis. The heavier pure iron spheroids deposit as a result of inertial impact. The mineral source of the molten phase is most likely illite. 

The reconstruction of the burial and thermal history of the Namorado Sandstone was performed using the BaSS software (Basin Simulation System) developed by Chang et a/. (1991). The calibration of the thermal history was carried out by measured vitrinite data and smectite/illite conversion rate. The amount of illite in the interlayered I/S clays was determined via XRD analysis. The organic matter residue of the associated shales close to the reservoir intervals was petrographically analysed to obtain the vitrinite index. Depth in the diagrams and tables is referred to datum level (driller-measured depth). 

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