Showing papers on "Vermiculite published in 1975"

Fire resistant vermiculite composition board and method of manufacture

Abstract: A fire resistant vermiculite composition board comprises, in percent by weight, from 40 to 90% heat expanded vermiculite particles; from 5 to 20% ceramic clay particles; from 10 to 30% hydrated cellulosic gel having a TAPPI drainage time of at least 900 seconds; from 1 to 20% defiberized wood; and from 1 to 20% starch. The vermiculite is in an incompletely expanded condition of a degree predetermined to permit its further expansion upon subsequent exposure to heat. This results in a corresponding expansion of the composition board of which it is a component when the board is exposed to fire, preventing the formation of cracks and insuring continued fire protecting coverage of the area across which the board is applied.

Experimental alteration of chlorites into vermiculites by chemical oxidation

Abstract: VERMICULITE and chlorite minerals occur commonly in soils where they may be an important source of magnesium and micronutrients. Vermiculite adsorbs and retains potassium and ammonium preferentially, which makes it particularly important in exchange reactions involving these cations. Like micas, chlorites in soils may weather to vermiculites1,2. Micas are readily altered to vermiculites in the laboratory by the extraction of potassium. It has not, however, been possible to alter unoxidised, true chlorites to vermiculites by extracting the hydroxide sheets using chemical techniques3,4 in the laboratory.

Natural chlorinated auxins labelled with radioactive chloride in immature seeds

Abstract: Immature seeds were harvested from 15 species grown in perlite/vermiculite containing 36Cl-, but with very low levels of cold Cl-. Autoradiograms of one- and two-dimensional thin layer chromatograms of butanol extracts of lyophilized seeds indicated several radioactive compounds besides the 36Cl- in many species. In pea the radioactivity cochromatographed with 4-(or 6-)chloroindolyl-3-acetic acid and its methyl ester; in other species radioactivity was found near these chlorinated indolyl-acetic acid markers.

Fine-grained Micas in Soils

Abstract: Fine-grained micas are present in nearly all soils. Frequently, they are the most abundant component of the clay fraction. In many soils, micas are the principal source of native potassium for plants. On weathering, micas are altered to vermiculite and sometimes to smectitelike minerals and, as such, significantly increase the cation exchange capacity and affect the relative selectivity by soils for various exchangeable cations.

A polarized infrared and X-ray study of lysine-vermiculite

Abstract: Lysine and vermiculite form a stable, ordered, interlamellar complex which has a well defined superlattice structure with respect to the ab-plane of vermiculite. The lysine molecules lie at a low angle to the silicate surfaces and establish a double layer network between such surfaces. I.R. and chemical data for the complex are given. The possible role of hydrogen bonds in linking the system together is considered.

Veränderungen von Dreischicht‐Tonmineralen durch natives K in holozänen Lößböden Mitteldeutschlands und Niederbayerns

Abstract: Changes of three-layer clay minerals by native K in holocene loess derived soils of Central Germany and Lower Bavaria. Transformations of the clay minerals illite, vermiculite and smectite were determined in Central German (31 profiles) and Lower Bavarian loess districts (5 profiles) using 31–36 soil properties. To get significant differences between solum and sediment, the multivariate diskriminant analysis was applied. In the Central German loess district the following properties were crucial, to receive significant separation between solum-horizons and sediments: smectite content, several values of potassium fixation, interlattice potassium. Important were also some parameter of the K-Ca-exchange curve: Activity ratio of a soil solution in equilibrium with a soil (ARo), buffering capacity of the soil for K at equilibrium (BCKE), labile K(K1), exchange capacity of the exchange sites with a specific affinity for K minus labile K(ECx—K1). The differences of these values can be explained by assuming that (at pH 6–7) the beidellitic layers of smectites of the parent loess were transformed to illitic layers in the solum-horizons. In the Lower Bavarian loess landscape potassium fixation, total K in clay fraction (< 2 μm) and the parameters of the K-Ca-exchange curve indicate the same clay mineral transformation as in Central Germany. Smectite values were not introduced to the diskriminant function, because they were highly significantly correlated with potassium fixation. In this case potassium fixation has caused a better separation between the solum-horizons and the parent loess than X-ray data. From these results, from total -K of the fraction 2–20μm (solum-horizons smaller than sediments) and the vermiculite content fo the clay fraction, it can be concluded, that the rate of potassium release from micas and the rate of potassium fixation by beidellitic sheets during the Holocene period were nearly equal.

Natural Alteration of Mica and Reactions between Released Ions in Mineral Deposits

Abstract: Chemical changes during the natural alteration of micas were studied by electron microprobe and classical chemical analyses of fresh and altered portions of mica flakes from 10 Canadian mineral deposits. Results of 50 new analyses are discussed in five examples, starting from simple changes in the interlayer followed by exsolution of titania and ending with complex replacements of anions and cations in all layers of the mica structure. Alteration of micas starts along 001 cleavage planes and fractures and gradually extends into the entire flake leaving some or no remnants of the host mica. The removal of ions from the mica structure and from the flake takes place by gradual depletion, by exsolution of oxides, and/or by alternating removal and redeposition of a newly-formed oxide, illustrated in the following example of the removal of Ti; Residual minerals replacing the original micas are secondary and recrystallized micas, chlorite, vermiculite, serpentine, talc and depleted, optically amorphous flakes. Newly-formed minerals which may incorporate the released ions into their structures are rutile, anatase, sericite, hydronepheline, chlorite-serpentine aggregates, goethite and jarosite. The following partly-altered micas are indicative of sulphide mineralization;

A quantitative method for the determination of montmorillonite in soils

Abstract: Abstraet--A quantitative method for determination of montmorillonite in the soil clay fraction, using X-ray spectrometry, is proposed. The method is based on the fact that polyvinylpyrrolidone (PVP) is adsorbed on the interlayer surfaces of montmorillonite, giving a first order c-axis spacing of 26/~, while it is not adsorbed on other swelling clays. The experimental conditions to obtain a maximum height of the X-ray diffraction peak, and the effect of the mass adsorption coefficient of vermiculite on the intensity of montmorillonite, were investigated. Soil montmorillonite was determined by the method of known additions, measuring the intensity of the X-ray diffraction peak before and after the addition of small and known amounts of Wyoming montmorillonite. Several methods have been proposed for 'the quantitative determination of montmorillonite in soil clays (Mehra and Jackson, 1959; McNeal and Sansoterra, 1964; Barshad, 1965; Alexiades and Jackson, 1965, 1966). These methods involve the simultaneous determination of montmorillonite and vermiculite, because these clays often occur together in the soil clay fraction, especially in arid and semi-arid soils (McNeal and Sansoterra, 1964; Levy et al., 1972). The methods

Sandstone‐derived soils of a catena at iperu, nigeria

Abstract: Summary Chemical and mineralogical properties of five soil profiles of a catena in Iperu, Western State of Nigeria, are reported. The pH values of the subsoils are extremely acid. Acidity decreases with improved drainage in the subsoils (pH 4.0–5.8). The cation exchange capacity (C.E.C.) of the soils range from 3.0 to 16.2 me/100g of soil. The silt: silt+clay ratio, calcium: magnesium ratio and Fe2O3:Al2O3 ratio are used as weathering indices. The low values of the silt: silt + clay index indicate that the soils must have undergone advanced weathering. The magnitude of the Ca: Mg ratio indicates that more calcium than magnesium is available in the soils. The values for sodium and potassium are extremely low. More iron than aluminium was extracted from the soils by the dithionite-citrate method. Kaolinite is the most abundant clay mineral. Halloysite, interstratified clay materials, vermiculite, quartz, and mica are present in considerable amounts. The silt fraction in which quartz is the most abundant mineral, also contain some kaolinite and mica.

Micaceous Vermiculite, Glauconite, and Mixed-Layered Kaolinite-Montmorillonite Examination by Ultramicrotomy and High Resolution Electron Microscopy

Abstract: Electron optical fringes of the layer structures of micaceous vermiculite (Colorado), glauconite (Wisconsin), and mixed-layered kaolinite-montmorillonite (Mexico) were observed after separation of clay fractions, saturation with various cations, embedment in Epoxy, thin sectioning normal to the (001) planes by a diamond-knife ultramicrotome, and high resolution, diffraction contrast electron microscopy. In the thin section of Cs-saturated micaceous vermiculite, the electron optical fringes at 10 A may represent the basal crystallographic spacing of unweathered K mica; fringes at 11 A and 5.5 A may represent the (001) and (002) crystallographic basal orders of Cs vermiculite with the interlayers nearly closed; and fringes at 12.5 A may represent incompletely collapsed vermiculite (possibly lower layer charge and/or hydrous metal oxide-interlayered). The K-saturated glauconite particles occur as thin crystal packets consisting of 5 to 20 layers of mica + vermiculite + montmorillonite with 10 A spacing; occasional interstratified 14 A spacings are believed to represent the Raman-Jackson chlorite. A Mg-saturated, mixed-layer kaolinite-montmorillonite from Mexico showed interleaving among the electron optical (001) fringes of kaolinite (7 A), montmorillonite (12 to 14 A), micaceous vermiculite (10 A), and regularly interstratified kaolinite-montmorillonite (19 A).

Expanded vermiculite as heat insulation material

Abstract: A heat insulation material of apparent density 0.5–0.6 g/cm3 and a refractoriness of 1500–1600°C was produced from expanded vermiculite, and a technology for producing ceramic vermiculite heat-insulation slabs was developed.

A kinetic survey of the cation exchange and of the oxidation of a vermiculite

Abstract: With the use of a BaCI 2 solution containing radioactive Ba 2+ ions, kinetics of cation exchange have been done on a Kenya vermiculite, natural on one hand and previously oxidized either by 50~ water or oxygenated water on the other hand. Correlatively, the quantity of ferric iron in the layer has been determined by E.P.R. These two methods have shown that during an oxidation the proportion of iron which stays in the octahedral layer depends upon the nature of the oxidizing agent. During a weak oxidation, the iron stays entirely in an octahedral layer and the exchange capacity of the vermiculite decreases; on the other hand, during an oxidation by oxygenated water, part of the iron is extracted from the octahedral layer and the exchange capacity of the vermiculite is not changed, as established by the studies Of Farmer (Farmer et al., 1971). Kinetic data for Llano vermiculite also are reported and compared with those for the Kenya vermiculite.

A vermiculite clay from Junosuando, Pajala county, northern Sweden

Abstract: A clay sample from northern Sweden has been studied by X-ray diffraction and chemical analysis. The chief clay mineral is an iron-rich vermiculite, which by glycolation partly expands to 16 A. The content of vermiculite and the proportion of expandable layers increase with smaller size fractions and towards the upper parts of the deposit. Other minerals present are plagioclase, quartz and amphiboles. The contents of both biotite and chlorite are markedly low. In this study, no connection has been found between the vermiculite and the weathering of amphiboles or biotite.

Clay minerals in soils derived from ultrabasic rocks of southern westland, New Zealand

Abstract: The clay mineralogy of four soil profiles derived from epidiorite, serpentinised peridotite, and serpentinite has been investigated by X-ray diffraction and electron optical procedures. The sand mineralogy of each soil, and the minerals in the fresh rocks, were determined by X-ray diffraction and optical methods. A weathering sequence was established in which ferromagnesian minerals, especially chrysotile and lizardite, have altered to vermiculite. In three profiles the vermiculite contained much interlayer material, and altered to chlorite, whereas in the fourth profile this mineral contained little interlayer material, and did not alter to chlorite. Lizardite may have an unusual tubular form.

Lightweight cement composition of enhanced trowelability

Abstract: The trowelability of lightweight aggregate-containing, low density cement compositions (eg Portland cement-expanded vermiculite composition(s) is enhanced by the incorporation therein of a polymer of ethylene oxide The composition has particular utility in the lining of in-ground swimming pools where the composition is to be applied by trowel to other than horizontal surfaces