Bentonite, constituents

A plugging slurry for oil and gas well drilling is given in Table 18-7 [1441]. It is formed by adding water to the Portland cement suspension containing the other three constituents. The bentonite clay powder is premixed with water... 

For compacted, low-permeability soil liners, the U.S. EPA draft guidance recommends natural soil materials, such as clays and silts. However, soils amended or blended with different additives (e.g., lime, cement, bentonite clays, and borrow clays) may also meet the current selection criteria of low hydraulic conductivity, or permeability, and sufficient thickness to prevent hazardous constituent migration out of the landfill unit. Therefore, U.S. EPA does not exclude compacted soil liners that contain these amendments. Additional factors affecting the design and construction of CCLs include plasticity index (PI), Atterburg limits, grain sizes, clay mineralogy, and attenuation properties. 

Kaolinite is the main constituent in china clay used to make porcelain. The layers are largely held together by van der Waals forces. Bentonite is used in cosmetics, as a filler for soaps, and as a plasticizer, and it is used in drilling-muds as a suspension stabilizer. Bentonite and kaolinite clays are used, after treatment with sulfuric acid to create acidic surface sites, as petroleum cracking catalysts. Asbestos also has a layered structure (Section 12.13). 

The aged pillaring reagents were heated to 65 C and 325 bentonite, American Colloid Company, whose major constituent is the layered clay mineral, montmorilIonite, was added. There was always a 5-fold excess of aluminum in solution and the volume of solution per gram of clay was always 45 cc/g or more. The reaction was carried out for 2 hours. The slurry was filtered and the solids washed two times with water, dried, sized, and calcined at 500 C for 2 hours in air. 

Montes (176) analysed the essential oil constituents using the principle of chromatographic adsorption with the aid of columns of silicic acid and bentonite. The compounds were then crystalized and their melting points were deter-det ermined. 

Weaver (1959) noted that the chlorite, which is a common constituent of the Ordovician K-bentonite beds of the eastern United States, has a dioctahedral 2 1 layer and a trioctahedral hydroxide sheet. A partial chemical analysis indicated the chlorite contained less than 2% Fe203. Both layers were probably formed in place from the alteration of volcanic ash in a marine environment. Only one other chlorite of this type had been detected in X-ray patterns of approximately 75,000 samples of sedimentary rocks. The other sample was from a Paleozoic argillaceous limestone at a depth of 24,400 ft. in Oklahoma. Chlorites of this type might well go undetected when chlorite is only a minor component. 

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%. 

A method used to solve the problems of excessive lees and flavor stripping caused by flning wine with bentonite is to ferment in contact with bentonite. Fermentation in the presence of bentonite is an old practice used in Europe for protein stabilization. Such a practice avoids or minimizes the need for subsequent bentonite addition into wine. Fermentation in contact with bentonite has several advantages (1) only juice components are adsorbed onto bentonite and not the fermentation-by products or barrel-aging constituents and (2) fermentation lees have a lower monetary value than do finished wine lees. Thus, protein stabilization or partial stabilization during fermentation may be an important economic consideration. 

Preferred bentonite clays are those whose chief constituent is mont-morillonite, a mineral of the composition corresponding to the empirical formula, 4Si02-Al203 H20. The principal sources of raw clay for the manufacture of the presently most widely used natural catalyst (Filtrol Corporation) are deposits in Arizona and Mississippi. The clay from these deposits contains appreciable amounts of impurities, principally CaO, MgO, and Fe203, which replace part of the A1203 in the ideal montmorillonite structure. The catalyst is prepared by leaching the raw clay with dilute sulfuric acid until about half of the alumina and associated impurities is removed. The resulting product is then washed, partially dried, and extruded into pellets, after which it is activated by calcination. A typical analysis of the finished catalyst is as follows (Mills, 12). 

Neokunibond Optigel CL Osmos N. Major constituent of Bentonite and Fuller s earth. Used as a binder and plasticizer for ceramic formulations ion exchange builder in detergents thixotropic agent for liq. soaps flocculant for water treatment. Industrial chromatographic techniques White powder bulk d = 300-370 g/l. Kaopolite. 

Neretnieks I (1982) Diffusivities of some dissolved constituents in compacted wet bentonite clay-MX80 and the impact of radionuclide migration in the buffer. SKBF/KBS Teknisk Rapport, Stockholm, p 82-87... 

Abstract We here treat a diffusion problem coupled with water flow in bentonite. The remarkable behavior originates from molecular characteristics of its constituent clay mineral, namely montmorillonite, and we show the behavior based on a unified simulation procedure starting with the molecular dynamic (MD) method and extending the obtained local characteristics to a macroscale behavior by the multiscale homogenization analysis (HA Sanchez-Palencia. 1980). Not only the macroscale effective diffusion property but also the adsorption behavior is well defined based on this method. 

Definitbn One of the montmorillonite minerals that are the principal constituent of bentonite clay Formula Nao (Mg,Li)6Si,02o(OH,F),... 

The health and environmental issues for nanoclays specifically are rninimal and manageable. Sister organoday products have been used for many years in a host of industrial and consumer products. The perception that nanoclays are somehow different because of the prefix nano may be the problem. Nanoclays only become nano when they are placed in a host-polymer matrix, whereupon they cannot be separated or distinguished form the bulk polymer and other constituents. Crystalline silica is a naturally occurring component that may be present in commercial alkyl quaternary ammonium bentonite (CAS No. 68953-58-2) at concentrations <0.5% [8]. Crystalline silica dust (see also Chapter 19) when inhaled is a health hazard in humans and is regulated to very low permissible exposure limits. 

Chemical Description One of the montmoriilonite minerals that are the principal constituents of bentonite clay... 

Example 5.1 (A constituent description of bentonite clay). Bentonite consists mainly of smectitic clay minerals such as montmorillonite and beidelite, with macro-grains that are mainly quartz and chalcedony. The chemical formulae of water and quartz are H2O and SiOa, respectively, and we assume that the chemical formula of a smectitic clay mineral is Nai/3Al2[Sin/3Ali/3]Oio(OH)2. Note that the sodium ions Na+ exist in an interlayer space of the clay minerals. For simplicity, the porosity is assumed to be n = 0.5, and the composition (i.e., mass fraction) of the solid phase is given as consisting of 50% clay minerals and 50% quartz. The pores are assumed to be filled with pure water. The REV is a 1 cm cube. 

The alkalinity of the fluid is also essential for corrosion control, rheological properties in bentonite mud, and for its reaction with some formation constituents. Water-based drilling mud (Spud Mud) commonly consists of bentonite clay (gel) accounting for around 10% of the mixture, with additives such as barium sulphate (barite), calcium carbonate (chalk) or hematite (e.g., HSL, 2000). In some cases (Natural Bentonite Mud), caustic soda (ca. 1% of the mud mass) is added to water and bentonite (ca. 9% of the mud mass) to stabilize the pH. The pH usually ranges between 9.5 and 10.5, but higher values are not uncommon (e g., Finger and Blankenship, 2010). 

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