Bentonite-quartz

Since granite and bentonite/quartz were decided to be the host rock and backfill material, respectively, at an early stage of the project, these two materials were studied for all of the 14 radionuclides selected and for both of the two artificial groundwaters given in Table II. The radionuclides used in the laboratory experiments are given in Table III. 

Figure 5. Range of distribution coefficients for bentonite/quartz mixture (10 90) at25°C(cf.TableVI)...

Bentonite is a rock rich in montmorillonite that has usually resulted from the alteration of volcanic dust (ash) of the intermediate (latitic) siliceous types. In general, reUcts of partially unaltered feldspar, quartz, or volcanic glass shards offer evidence of the parent rock. Most adsorbent clays, bleaching clays, and many clay catalysts are smectites, although some are palygorskite [1337-76 ]. 

Other factors must also be considered. Similarly the replacement of 1 % milling clay by /4% of the more colloidal bentonite is beneficial. Large additions of quartz at the mill improve heat resistance and, provided the firing temperature is increased to dissolve a sufficient quantity of this silica in the glass, the acid resistance is also enhanced. 

The Fe-B nanocomposite was synthesized by the so-called pillaring technique using layered bentonite clay as the starting material. The detailed procedures were described in our previous study [4]. X-ray diffraction (XRD) analysis revealed that the Fe-B nanocomposite mainly consists of Fc203 (hematite) and Si02 (quartz). The bulk Fe concentration of the Fe-B nanocomposite measured by a JOEL X-ray Reflective Fluorescence spectrometer (Model JSX 3201Z) is 31.8%. The Fe surface atomic concentration of Fe-B nanocomposite determined by an X-ray photoelectron spectrometer (Model PHI5600) is 12.25 (at%). The BET specific surface area is 280 m /g. The particle size determined by a transmission electron microscope (JOEL 2010) is from 20 to 200 nm. 

Hybrid catalysts consisting of a zeolite (ZSM-5 or Beta) and bentonite as a binder were prepared and characterized by XRD, pyridine FTIR and nitrogen adsorption. The hybrid catalysts exhibited similar properties as the combined starting materials. Catalytic pyrolysis over pure ZSM-5 and Beta as well as hybrid catalysts has been successfully carried out in a dual-fluidized bed reactor. De-oxygenation of the produced bio-oil over the different zeolitic materials was increased compared to non-catalytic pyrolysis over quartz sand. 

The origin of Aeolian dust from Chinese desert to Japanese islands was studied with ESR of dust, mostly fine grains of quartz.132 Suspended particulate matter (SPM) collected by environmental protection agency was measured with ESR.133 Dust soot of automobiles was also measured to check the motor combustion rate. Adsorption of NO, Mn2+ and Gd3 on clay minerals, bentonite and se-piolite134 has been studied using paramagnetic ions as tracers for radioactive elements. And studies have been carried out on how divalent and trivalent cations diffuse and blocked by surrounding clay minerals, in the context of their leak from nuclear waste repository to the environment.135... 

In the Swedish KBS-project a mixture of bentonite and quartz (10 90) or compacted bentonite were proposed at an early stage as possible backfill materials. Bentonite is a rather common mont-morillonitic clay with good mechanical properties and chemical... 

In our studies, the model substance (montmorillonite) was a calcium bentonite (Istenmezeje, Hungary), the characteristic features of which are given here. X-ray diffraction (intensity of the basal reflection) and thermoanalytical (weight loss upon heating) data show 91% montmorillonite content. The other constituents are 5% calcite, 3% kaolinite, 1% x-ray amorphous silicates, and a trace of quartz. The amorphous phase is silicate particles, which are not crystalline for... 

Obviously, the dissolution of the elements leads to change in the crystal lattice and the mineral composition. This can well be seen during the acidic treatment of montmorillonite or bentonite for catalytic purposes (Section 2.1). The treatment is done using concentrated hydrochloric, sulfuric, or phosphoric acid. X-ray diffraction studies show that a commercially available montmorillonite has low montmorillonite content (53%). The other constituents are illite 10%, kaolinite 6%, quartz 10%, plagioclase 5%, gypsum 1%, anhydrite 4%, and amorphous 7%. 

FIGURE 3.3 X-ray diffractograms of the B-I.b. bentonite sample (sedimentary) (upper) and B-II.b. upper bentonite sample (bentonitized tuff) (lower), mm = montmorillonite, ab = albite (plagioclase), q = quartz, i = illite, s = sanidine (feldspar). (Reprinted from Nagy and Konya 2005, with permission from Elsevier.)... 

Similar to the quartz samples, asphericity and volume-to-surface ratio of the trapped inclusions changed upon addition of the salt - but more drastically in the case of bentonite. 

Unmodified acid clays have been little utilized as catalysts for Friedel-Crafts acylation reaction. Among the scanty information from the literature, the production of AQ 22 through cyclodehydration of BBA 21 is of some interest (Scheme 4.22). The reaction is performed in the presence of different clays at 350°C for 30 min. AQ 22 is directly recovered by sublimation from the reaction mixture. Some interesting results are achieved with commercially available catalysts such as Tonsil BW3, a mixture of mica, quartz, feldspar, and amorphous silica with bentonite and mont-morillonite KIO, product 22 being obtained in 78%-89% yield. Reusability studies show that Tonsil BW3 still gives product 22 in 60% yield after five... 

Explosive volcanism in western North America 95 million years ago (Late Cretaceous age 42) spread volcanic ash downwind to the east of the volcanoes. Upon deposition, the volcanic ash was chemically altered (e.g., devitrification of volcanic glass) to form bentonite, in which montmorillonite is the dominant mineral. In addition, the Late Cretaceous bentonites contain low abundances of magmatic minerals (e.g., quartz, alkali-rich feldspar, zircon, biotite) that were quenched during the volcanic eruption 43, 44) and entrained in the volcanic ash. The explosive volcanic events are known to have produced ash having a granitic composition 40). 

Saturated bentonite consists of hydrated smectite minerals, mainly montmorillonite, and quartz particles, called the macro-grain. See a schematic diagram of the microstructure given in Figure 1. 

We assume mesoscale and microscale domains are periodic (Figure 5). Let ar , and jc be coordinate systems defined in macro-domain 2o, meso-domain Qi and micro-domain If we perform a laboratory seepage/consolidation test on a typical Japanese bentonite, Kunigel VI, the macroscale specimen is of scale lO m, the mesoscale quartz grains are of lO m, and the microscale clay minerals are of 10 m. So, we estimate the scale factor =10 , and introduce the relations x = x°/z, x = x /e. 

The target bentonite, Kunigel VI, consists of about 50% of montmorillonite in weight and the rest of macro-grains, mainly quartz particles. The mass density of a crystal is 2.7g/cm, both for montmorillonite and for quartz, so one third (1/3) of the bentonite with its dry density 1.8g/cm is void (i.e., the void ratio e=0.5). Based on a... 

Silicon Silicone Silica Siliceous—Silicon is a chemical element silicones are plastic organic substances containing the element silicon silica is a general term for minerals (such as quartz sand) consisting of an oxide of silicon. Siliceous material includes more complex inorganic compounds such as glass, asbestos, bentonite. 

In general, waste green sand consists of about 80 % quartz sand grains and about 20 % fines (bentonite, coal dust, etc,). Out of 100 % waste sand, about 70 % is transferred back to the core-making as reclaimed sand. The degree of efficiency with regard to quartz is about 88 %. 

In mixed organic-bentonite sands, cured bentonite and organic binders are present on the sand grains. The dust is composed of active and cured bentonite, coal dust (only for iron foundries), quartz fines and organic binder residues. Mixed sands occur mainly in iron foundries and represent some 75 % of the total used sand production. The regeneration can be performed using mechanical, pneumatic, thermal or combined systems. 

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