Clays mineral properties

RICH (C. I.) and OBERSHAIN (S.S.), 1955. Chemical and clay mineral properties of a red-yellow podzolic soil derived from a muscovite schist. Soil Sci. Ame. Proc. jL9, 334-9. 

Odlyha et al. (1992) Odlyha, M. Walker, R.M. Liddell, W.H. A study of the effects of conservation treatment on the Ranshawe archive Conservation of the Iberian and Latin American Cultural Heritage preprints of the contributions to the lie Madrid Congress, 9-12 September 1992 Hodges, H.W.M. Mills, John S. Smith, Perry (eds.) IIC, London (1992) 104—111 Odom (1984) Odom, l.E. Smectite clay minerals properties and uses Philosophic Transactions of the Royal Society, London A311 (1984) 391 09... 

FIGURE 1.6 Clay minerals and some clay mineral properties. Compiled after Jorden and Campbell (1984). 

TABLE 1.2 Typical Values for Clay Mineral Properties (Ellis and Singer, 2007) Specific Internal CEC in Wet Clay ... 

Clay-bound water creates the shortest relaxation time. This clay mineral-bound water effect is controlled by clay mineral properties. Therefore, relaxation time correlates with other interface properties of clay minerals such as specific internal surface and cation exchange capacity (CEC Table 3.3). Thus, T2 could be used as a CEC indicator (see, for example, Martin and Dacy, 2004). 

Because clays (rocks) usually contain more than one mineral and the various clay minerals differ in chemical and physical properties, the term clay may signify entirely different things to different clay users. Whereas the geologist views clay as a raw material for shale, the pedologist as a dynamic system to support plant life, and the ceramist as a body to be processed in preparation for vitrification, the chemist and technologist view clay as a catalyst, adsorbent, filler, coater, or source of aluminum or lithium compounds, etc. 

J) The extreme fineness of iadividual clay particles, which may be of colloidal size ia at least one dimension. Clay minerals are usually platy ia shape, and less often lathlike and tubular or scroU shaped (13). Because of this fineness clays exhibit the surface chemical properties of coUoids (qv) (14). Some clays possess relatively open crystal lattices and show internal surface colloidal effects. Other minerals and rock particles, which are not hydrous aluminosihcates but which also show colloidal dimensions and characteristics, may occur intimately intermixed with the clay minerals and play an essential role. 

The multitude of variation in clay minerals is caused by substitution in the octahedral and tetrahedral layers resulting in charge deficits. The manner in which the charge deficit is balanced leads to many of the useful and unique properties of clay minerals. 

Smectites are stmcturaUy similar to pyrophylUte [12269-78-2] or talc [14807-96-6], but differ by substitutions mainly in the octahedral layers. Some substitution may occur for Si in the tetrahedral layer, and by F for OH in the stmcture. Deficit charges in smectite are compensated by cations (usually Na, Ca, K) sorbed between the three-layer (two tetrahedral and one octahedral, hence 2 1) clay mineral sandwiches. These are held relatively loosely, although stoichiometricaUy, and give rise to the significant cation exchange properties of the smectite. Representative analyses of smectite minerals are given in Table 3. The deterrnination of a complete set of optical constants of the smectite group is usually not possible because the individual crystals are too small. Representative optical measurements may, however, be found in the Uterature (42,107). 

The hydrated alumina minerals usually occur in ooUtic stmctures (small spherical to eUipsoidal bodies the size of BB shot, about 2 mm in diameter) and also in larger and smaller stmctures. They impart harshness and resist fusion or fuse with difficulty in sodium carbonate, and may be suspected if the raw clay analyzes at more than 40% AI2O2. Optical properties are radically different from those of common clay minerals, and x-ray diffraction patterns and differential thermal analysis curves are distinctive. 

MiscelDneous. Other important properties are resistance to thermal shock, attack by slag, and, in the case of refractories (qv), thermal expansion. For whiteware, translucency, acceptance of glazes, etc, may be extremely important. These properties depend on the clay mineral composition, the method of manufacture and impurity content. 

Tablet press Molding press Pellet mill 10 Up to 1 ton/hr flow and mechanical properties plastic preforms, metal parts, ceramics, clays, minerals, animal feeds...

As an example, the migration of clay from the surface of a soil to a lower horizon results from several processes occurring when certain soil and environmental properties exist. First, claysized minerals must form, usually requiring weathering to have occurred. Clay minerals formed in the surface soil can then go into suspension when salt concentrations in solution are low. Seasonal rains can move the clay down... 

Rosenqvist, I. T. (1962). The influence of physicochemical factors upon the mechanical properties of clays. Proc. 9th Nat. Conf. on Clays and Clay Minerals, pp. 12-27. 

Collins, Y.E. and Stotzky, G., Heavy metals alter the electrokinetic properties of bacteria, yeasts, and clay minerals, Appl Environ Microbiol, 58 (5), 1592-1600, 1992. 

Primary clay is also known as residual clay, indicating that they are either the in situ residue of one type of weathered rock or the transported residue of many types of rocks most primary clay deposits occur, however, in situ, at the location where the clay particles were formed. The clay is usually quite pure and colorless or white, but very small relative amounts of minerals mixed with the clay, such as quartz and/or iron oxides, may impart to it a yellow, brown, or green color. Primary clay is also characterized by the extreme fineness of its particles, which usually measure below 2 micrometers (0.002 mm) in diameter. The more than 20 different types of primary clay minerals can be distinguished by their chemical composition, which varies widely, and by their physical properties. Primary clays that have been used for making ceramic objects are listed in Table 55. 

Montmorillonite, also one of the most common clay minerals, occurs as a soft rock after it is powdered and mixed with water, it acquires plastic properties. It is the main constituent offuller s earth, used since antiquity for fulling (cleansing textile cloth). 

Solutions of TKPP have been shown to have unique and advantageous properties for use in formulating a wide variety of well fluids. Its reasonable cost, worldwide availability, and nontoxic properties make it a preferred additive for use in many petroleum applications. It has been shown to be a most effective salt with respect to inhibiting hydration and swelling of clay minerals commonly encountered in drilling operations and/or reservoirs. Avoiding clay problems is the major impetus for the incorporation of potassium ions in well fluids, and the use of TKPP provides advantages over and above those available from other potassium salts. 

A combination of SIPS with the stabilising and synthesis-favouring properties of clay minerals was studied by Rode et al. (1999) in experiments involving dry/wet cycles. The simultaneous use of both SIPS and clay minerals as catalytically active surfaces led to peptides up to and including the hexamer (Gly)6. The question as to whether this technique fulfils prebiotic conditions can (within certain limitations) be answered positively, since periodic evaporation phases in limited areas (lagoons, ponds) are conceivable. The container material could have consisted of clay minerals. Further progress in the area of peptide synthesis under conditions which could have been present on the primeval Earth can be expected. 

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