Showing papers on "Vermiculite published in 1968"

Aluminum interlayers in layer silicates; Effect of OH/ Al ratio of Al solution, time of reaction, and type of structure

Abstract: Aluminum intertayers were synthesized under the same experimental conditions in a number of vermiculites and montmorillonites from different sources to determine the effects of the degree of neutralization of AI solutions, the time of reaction, and the' type of structure. Vermiculite fixed AI as well as hydroxy-Al ions in its interlayers, producing a stable 14 ,~ spacing and decreasing its cation exchange capacity considerably. Heating the Al-interlayered vermiculite at 300~ produced an interstratified mixture, indicating that some interlayers collapsed while others did not. The different collapse was attributed to different charge on vermiculite layers. Neither the aging of vermiculite in AI solutions nor their OH/AI ratios changed the stability of the interlayers appreciably. Montmorillonites, on the other hand, did not fix AI ions but fixed appreciable amounts ofhydroxy- AI ions. In addition, the stability of the interlayers in montmorillonite increased on aging in hydroxy- A1 solutions and exceeded the stability of the interlayers produced in vermiculite. To explain the greater stability of montmorillonite interlayers, it was postulated that the more expanded interlayer space in montmorillonite provides a favorable locale for the organization of hydroxy-A1 ions into gibbsite structure while the restricted expansion in vermiculite prevents it.

Oxidation of ferrous iron in vermiculite and biotite alters fixation and replaceability of potassium.

Abstract: Oxidation of octahedral ferrous to ferric iron in soil vermiculite clays and biotites increases the potassium-fixation capacity of vermiculites and increases the difficulty of replacing interlayer potassium in biotites. This unexpected effect is believed to be related to an increase in the attractive forces between potassium ions and oxygen ions of the surface layers which is brought about by a tilting of the dipole of the octahedral hydroxyl ions from a perpendicular position to an inclined position with respect to the cleavage plane.

Formation of Hydroxy-Al and -Fe Interlayers in Montmorillonite and Vermiculite: Influence of Particle Size and Temperature

Abstract: Hydroxy-Al and -Fe interlayers were prepared in "mono-mineralic" fine and coarse clay montmorillonite and coarse clay and silt vermiculite at 3~ and 21~ The formation of hydroxy interlayers was evaluated by X-ray diffraction, cation exchange capacity, and chemical analyses. At comparable particle size and regardless of temperature, the amounts of hydroxy-Al and -Fe interlayers in montmorillonite exceeded by far those formed in vermiculite. Likewise, the aluminum systems exhibited a higher degree of interlayering than iron systems. Within montmorillonite, the amount of hydroxy-A1 and -Fe interlayers increased as the particle size decreased, regardless of temperature. The aluminum interlayered montmorillonite equilibrated at 3~ was characterized by basal spacings of about 17 ,~ after Ca-saturation plus 54 per cent relative humidity. These spacings are larger than those normally observed for smectites. Within vermiculite systems equilibrated at 3~ more hydroxy-AI interlayers were recorded in coarse clay than in silt fraction, whereas at 2 I~ about equal amounts of interlayers were formed. By contrast, hydroxy-Fe interlayer was favored by the silt fraction at both temperature levels. The formation of aluminum interlayers in both minerals increased with increasing temperature. The formation of hydroxy-Fe interlayers in montmorillonite was generally not temperature dependent, whereas the formation of such interlayers in vermiculite increased slightly with increasing temperature. These data may partially explain the formation of chloritic intergrades in soils as a function of type of minerals, kind of ions, and thermal variations.

On the Chemistry of Clay

Abstract: Kaolinite, illite, chlorite, montmorillonite, and vermiculite are among the most important of the clay minerals. Cations are embedded between the silicate layers and on the basal faces of the crystals. Whereas only the cations on the outer faces are exchangeable in the first three of the above minerals, those between the layers can also be replaced by others in montmorillonite and vermiculite. These characteristics and the ability of montmorillonite and vermiculite to undergo intracrystalline swelling and to form inclusion compounds are responsible for the industrial importance of kaolin and clay. The structure of halloysite is particularly interesting, since the silicate layers in this case are rolled up to form tabes. The possible role of the clay minerals as catalysts in the formation of petroleum and in the beginning of life is finally discussed.

Ferrous-Ferric Ratio and CEC Changes on Deferration of Weathered Micaceous Vermiculite

Abstract: Ferrous iron in the layers increased 2-fold or more on deferration of coarser fractions of micaceous vermiculite naturally weathered from biotite (Colorado and Transvaal sources) The ferric iron content of the layers was decreased by the deferration treatment but the original content was restored by subsequent H2O2 treatment Sesquioxide coatings on micaceous vermiculite from Colorado, examined electron microscopically, were composed predominantly of Fe2O3 (80 to 85 percent), along with Al2O2 and SiO2 The CEC increased from 64 to 95 meq per 100 g in the fraction coarser than 1000 microns and 50 to 64 meq per 100 g in the fraction 2–02, microns in diameter, as a result of removal by deferration of positively charged sesquioxide coating which had originally blocked a portion of the CEC Although treatment with H2O2 after deferration restored the Fe3+ content to approximately the original value, the CEC was not affected probably because of deprotonation OH− O2− + H+ occurring simultaneous with Fe2+ Fe3+

Restricted, anisotropic diffusion and anisotropic nuclear spin relaxation of protons in hydrated vermiculite crystals

Abstract: The diffusion of water protons in hydrated vermiculite crystals has been studied by the pulsed magnetic-field gradient, spin-echo technique. Li+ and n-butylammonium ion-exchanged vermiculites have been swollen with water to basal spacings between the parallel silicate layers from 100 to 1030 A. In this state, self-diffusion has been studied as a function of sample orientation and diffusion time (from 3 to 11 msec). Diffusion is seen to be anisotropic with the behavior perpendicular to the layers differing from that parallel to the layers. Parallel to the layers, the protons move freely as if in liquid water except for a small fraction affected by buckled layers. Perpendicular to the layers, as many as half the protons behave as if in liquid water; presumably they are moving in large cracks in the lattice. The remainder of the protons are interpreted as confined to “pores” of average sizes ranging from 200 to 1800 A (relative to the unswollen lattice). Our estimates of the “pore” size are consistent with electron microscope studies by other workers. Because of the restrictions afforded by these “pores”, it is necessary to interpret the data in terms of a model which does not follow Fick's law. There is evidence of morphological changes attending swelling. It is determined that for the systems studied, Young River, West Australia vermiculite had the least water in “pores,” whereas Libby, Montana hydrobiotite contained the most buckles. Kenya vermiculite was also studied. Detailed studies of T1 and T2 indidicate single relaxation times which are anisotropic. The longer times are always observed with the vermiculite layers parallel to the magnetic field; increasing the basal spacing also increases the relaxation times. The relaxation anisotropy is attributed to anisotropic paramagnetism of the iron-filled vermiculite layers.

Calcium: aluminium exchange equilibria in clay minerals and acid soils1

Abstract: Summary Exchange reactions between 0.0in AlCl3 solutions of different pH and Ca-saturated montmorillonite, vermiculite, illite, and soils from the Park Grass Experiment at Rothamsted and the Deerpark Experiment, Wexford, Ireland, showed that Al3+ and Al(OH)2+ were adsorbed from solutions of pH > 4.0 and Al3+ and H+ from solutions of pH < 3.0. When Al was adsorbed, the cation exchange capacity of Ca-saturated soils and clays increased. Conventional Ca: Al exchange isotherms showed that Al3+ was strongly preferred to Ca2+ on all soils and clays. The equilibrium constant for Ca: Al exchange, K, was identical for soils before and after oxidizing their organic matter and did not vary, for any exchanger, with Al-saturation or the initial pH of the AlCl3 solution. This proved the validity of the procedure used for calculating exchangeable Al3+. K values for Ca:Al exchange favoured Al3+ in the order: vermiculite > Park Grass soil > Deerpark soil > illite > montmorillonite. The influence of surface-charge densities of the clay minerals on this order is discussed and a method proposed and tested for calculating the K value of a soil from its mineralogical composition.

Improved vermiculite and uses thereof

Abstract: 1,202,097. Delaminated, exfoliated vermiculite; cement compositions. MANDOVAL Ltd. 24 Feb., 1969 [21 March, 1968; 10 April, 1968 (2); 6 June, 1968], Nos. 13825/68, 17415/68, 17418/68 and 27019/68. Headings CIA and ClH. [Also in Division C4] Delaminated, exfoliated vermiculite is claimed per se. It has a flake like form with a width to thickness ratio preferably 3 : 1. It may be prepared by treating exfoliated vermiculite in a sheer action mill such as a hammer mill, the exfoliated vermiculite being preferably fed to the mill by way of an Archimedes screw. The product leaves the mill preferably by way of a herringbone pattern slotted screen. By mixing with binder(s) and optionally filler(s) a sealing or coating composition is obtained (see Divisions A5 and C4). The average largest dimensions of the vermiculite particles in these compositions is preferably not greater than “-inch. The binder may be a clay binder or an hydraulic binder, and the filler may be selected from ground chalk or limestone, pulverized fly ash, and lime. Coatings of delaminated exfoliated vermiculite have the laminµ substantially parallel to the coated surface and are consequently gas and liquid impermeable. Such compositions contain up to 50% by volume of a binder which may be ordinary Portland cement, white, sulphate resisting or rapid hardening Portland cement, lime or high alumina cement or mixtures thereof.

Asphaltic based fire-resistant compositions utilizing vermiculite ore intumescing agent

Abstract: FIRE-RESISTANT ASPHATIC COMPOSITIONS ARE MADE BY COMBINING: (A) ASPHALT HAVING A PENETRATION OF FROM 0 TO 50 MM./ 10 AT 77*F. AND A SOFTENING POINT OF FROM 150 TO 300*F.; (B) A NONCOMBUSTIBLE FIBROUS MATERIAL SUCH AS ASBESTOS OR FIBER GLASS; (C) A FINELY DIVIDED POROUS AGGREGATE SUCH AS PERLITE OR GROUND FOAMED POLYURETHANE; (D) A FINELY DIVIDED HEAT-FUSIBLE MATERIAL SUCH AS BOXAX GLASS OR BORIC ACID; (E) A VERMICULITE ORE INTUMESCING AGENT; AND (F) A SOLVENT FOR THE ASPHALT TO LOWER VISCOSITY OF THE COMPOSITION TO A POINT WHERE IT CAN BE APPLIED TO A SURFACE.

Process of clarifying solids water suspension

Abstract: 1,214,532. Clay treatment; clarification of suspensions by flocculation. SIMONACCO Ltd. 31 Jan., 1968 [16 Feb., 1967], No. 4929/68. Headings C1A and ClC. A solids/water suspension is clarified by a process which comprises forming flocs containing solids of suspension by adding to the suspension at least one phyllosilicate and at least one organic compound capable of bonding with the phyllosilicate(s) to form a complex and thereafter separating the flocs from the liquid phase, the phyllosilicate(s) having been activated by ion exchange and thereafter dispersed in an aqueous medium. The phyllosilicate(s) may be in any of the hydrogen, sodium, potassium and ammonium forms and may be provided by at least one clay material, for example montmorillonite, beidellite, hectonite, saponite, non- tronile, vermiculite, allevardite, illite, helloysite kaolinite, glauconite and mixtures thereof; the particle size of the dispersed phyllosilicate(s) preferably is not less than 0-05 microns. The organic compound(s) may contain a hydroxyl, carbonyl, imido, imino, carboxyl or carboxyalkyl group and may be monomeric, oligomeric or polymeric; compounds capable of forming hydrogen bonds are preferred. Compounds exemplified are polyacrylamide; polyacrylonitrile; carboxyalkylcellulose, for example carboxymethyl cellulose; sodium alkyl cellulose; organic acids, for example tannins and glue; sclero-proteins; ethylene diamine and diethylene triamine. It is preferred to use, for each litre of suspension to be clarified, between 10 and 3000 mg of phyllosilicate and not less than 0-01 mg. of organic compound which may be used in the form of a solution having a concentration of between 0-01 and 5% by volume. The flocs may be separated from the liquid phase by centrifuging, for example by use of a hydrocyclone or other mechanical means. It is preferred that the formation of flocs is reversible so that, if desired, separated flocs containing solids of suspension may be recycled wholly or partly for further clarification of a solids/water suspension. The solids/water suspension may be surface waters, industrial waste waters and effluents; examples relate to the clarification of river water, mine water and water which contains particles of wood fibre. In Example 11, clarification is preceded by softening of the water by addition thereto of milk of lime. Example 1 describes the preparation of activated phyllosilicate by grinding raw bentonite with soda, dispersing the bentonite-soda mixture in water, evaporating the dispersion over a water bath, suspending the resulting residue in water and separating from the resulting suspension, by settling or by the use of a centrifuge, for example a hydrocyclone, sodium-montmorillonite having a particle size below 30 microns; a coarse-grained clay mineral may be used in place of bentonite, which mineral is swollen in water and compounded with soda, sodium phosphate, sodium fluoride or an " alkali-hydrogen carbonate " by wet grinding prior to being dispersed in water and further treated as set forth supra.

Crystalline clay minerals of the soils derived from recent volcanic ashes in Hokkaido, Japan: II. 2:1 Type Clay Minerals

Abstract: In the previous study on clay minerals in the soils derived from recent volcanic ashes, it has been shown that expanding layer silicates with more or less interlayer-Al are found in large amounts among crystalline clay minerals, and that chlorite, illite and possibly kaolin minerals are found in small amounts (1). Montmori11onite shows a tendency to be dominant in the soils of the younger group and to be less Alinterlayered, However, vermiculite tends to increase, and both montmorillonite and vermiculite become more Al-interlayered in the soils of the older group. The purpose of the present report is to investigate 2: 1 type clay minerals, chiefly expanding layer silicates.

Asbestos materials of high dielectric strength and method of making same

Abstract: (1) ASBESTOS ARTICLES OF IMPROVED DIELECTRIC STRENGTH ARE MADE BY DISTRIBUTING PULVERULENT EXFOLIATED VERMICULITE THROUGHOUT AN ASBESTOS FIBER-BINDER COMPOSITION; APPROXIMATELY 1 PART OF VERIMCULITE IS PRESENT PER 1-5 PARTS OF ASBESTOS. (2) A MATERIAL OF GREAT DIELECTRIC STRENGTH IS MADE BY WETTING THE ORDINARY SHEET OF THE ABOVE COMPOSITION WITH WATER SOLUTIONS OF ALUMINUM PHOSPHATE OR CERTAIN SILICO FLUORIDES, PRESSING THE WET SHEET AT ELEVATED PRESSURE FOR A TIME TO INCREASE THE DENSITY THEREOF AND, THEN DRYING THE WET, PRESSED ARTICLE.

Effect of ammonium salts on the intake of phosphate by Indian clay minerals

Abstract: Phosphate fixation by kaolinite, muscovite, phlogopite, biotite and vermiculite from aqueous systems in presence of different quantities of ammonium sulphate, ammonium nitrate and ammonium chloride, have been studied. It is observed that the ammonium salts induce graeter phosphate fixation in presence of kaolinite and partly in presence of phlogopite, biotite and vermiculite.