Smectites rotation

ESR studies of other paramagnetic metal ions (Mn " ", VC)2+) as surface probes have confirmed that cation rotational mobility on fully wetted smectites with interlayer spacings of 1.0 nm or more is not more than 50% reduced relative to aqueous solution (12, 14). Apparently, about four molecular layers of water in the interlayer provide sufficient space for solution-like rotation rates of hydrated metal ions. 

Mathieson AMcL, Walker GF (1954) Crystal stracture of magnesium vermiculite. Am Mineral 39 231-255 Mazzucato E, Artioli G, Gualtieri A (1999) High temperature dehydroxylation of muscovite-2Mi a kinetic study by in situ XRPD. Phys Chem Minerals 26 375-381 McCarty DK, Reynolds RC Jr (1995) Rotationally disordered illite/smectite in Paleozoic K-bentonites. Clays Clay Minerals 43 271-284... 

A series of ID and 2D NMR experiments performed on nanocomposites of hectorite, a smectite clay mineral, showed new opportunities for studying large assemblies of layered minerals with polymeric materials.In particular. rotational-echo double-resonance (REDOR) experiments afforded H- Si distances with precision, and a mobility gradient of intercalated polyethyleneoxide (PEG) segments was demonstrated in H-" Si wideline separation (WISE) experiments. 

The raw bentonite is so uniform and rich in smectite that only simple drying in the sun of the excavated material with subsequent grinding is required at the quarries and plants. However, in most cases the clay material must be dried in rotating kilns, and also transformed to a suitable Na -rich form. 

A nickel laterite from Piaui, Brazil was used in this study. The top size of the ore was limited to 12.5 mm. The nickel laterite was composed mainly of quartz, silico-femiginous plasma, and clay minerals. The nickel content is 0.9%. The main nickel-bearing minerals are chlorite, smectite, vermiculite, manganese oxide and silico-ferruginous plasma [6]. Since moisture content, acid concentration, retention time and drum rotation speed are operating factors in drum agglomeration, they were investigated in this study. 

The ordered state of a smectite (beidellite) can be transformed into the semi-ordered state under the effect of a process of cation exchange. The exchange process (stirring in a saline solution) can produce rotations of layers of a multiple (arbitrary) of 60°. 

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