Showing papers on "Vermiculite published in 1990"

Nature and origin of an aluminous vermiculitic weathering product in acid soils from upland catchments in scotland

Abstract: A B S T R A C T: Vermiculitization of mica is one of the main weathering processes in soils from three upland catchments receiving various levels of acid deposition. Usually this process is manifested by the presence of interstratified mica-vermiculite with the interlayer space in the vermiculite often partially filled with polymeric hydroxyaluminium species. In one peaty podzol, regularly interstratified mica-vermiculite clearly develops at the expense of mica and is the dominant mineral in the Eh horizon. It was concentrated by chemical treatments to remove organic matter, free iron oxides, and any AI species in the interlayer, and the structural formula calculated from chemical analysis confirmed the dioctahedral character of both vermiculite and mica components, and indicated that the vermiculitic weathering product was formed from a dioctahedral mica. The degree of interlayering in the interstratified phases seemed to he pH-dependent with resultant implications for soil and freshwater acidification.

Weathering of biotite into dioctahedral clay minerals

Abstract: A B S T R A C T : Changes which occur during the natural weathering of biotite in granite gneiss and associated soils are measured by microanalysis and illustrated by SEM. Biotite weathers through a series of interstratified minerals to vermiculite and/or smectite phases which decompose rapidly to kaolinite. Both vermiculite and smectite phases appear to be dioctahedral, on the basis of chemical compositions derived from microprobe data. Weathering products are first apparent on the edges of laminae, where interstratified minerals are formed at right angles to both the edge face and the cleavage. Weathering soon develops along cleavage planes, initially most strongly near the edges of flakes, but then permeating extensively into the body of flakes and subdivided segments. The orientation of interstratified minerals and kaolinite within cleavages is parallel to the cleavage. Oxidation of Fe in biotite causes internal stresses which are relieved by physical deformation of the crystals. This accelerates chemical decomposition, particularly along cleavage planes. At an advanced stage of weathering when decomposition is active at many cleavages, biotite deteriorates to very finely divided, wafery remnants consisting of thin laminae separated by more open layers of particulate clay. Parts of the thin laminae remain relatively unweathered and have the same chemical composition as the original biotite immediately after oxidation. These relatively unweathered layers within the laminae have X-ray diffraction (XRD) characteristics of trioctahedral illite and they persist when the biotite remnants are broken up into clay (Fordham, 1989b). Other decomposition products are also formed. Some occur in sufficient bulk (at the microanalytical scale) to be identified directly by microprobe, but the chemical composition of others must be estimated by graphical procedures (Fordham, 1989a). These additional decomposition products of biotite are the subject of the present paper. Their formation in different parts of biotite flakes taken from different locations within the soil profile is described, and the weathering sequence as a whole is discussed. Microanalyses were performed on both thin sections and whole specimens, and the products are illustrated by scanning electron microscopy (SEM).

Procedure for Determining Sodium-Calcium Selectivity in Calcareous and Gypsiferous Soils

Abstract: A procedure to determine the exchanger-phase composition (and thus the Na/Ca selectivity) of calcareous and gypsiferous soils was developed and tested on three soils and three phyllosilicate minerals The procedure corrects for anion exclusion and mineral weathering by measuring the Cl, SO,,, and HCO3 in the soil solution and in the extracting solution Anion exclusion was found to be significant in the montmorillonite system, but generally less than 10% of the cation-exchange capacity in the soil, illite, and vermiculite systems Mineral weathering contributed significantly to the total extracted Ca Thus, exchangeable-Ca values were overestimated by 30 to 500% in the gypsiferous soils and 3 to 20% in the calcareous soils when weathering was neglected The proposed method allows the determination of cation-exchange capacity, exchangeable-cation composition, and anion exclusion at any solution composition, concentra-

Low temperature expandable vermiculite and intumescent sheet material containing same

Abstract: A method of decreasing the expansion temperature and improving the expansion characteristics of vermiculite ore comprising subjecting vermiculite ore containing interlamellar cations to a potassium nitrate solution for a time interval sufficient to ion-exchange interlamellar cations within said ore with potassium ions. Subsequent to this ion exchange the low temperature expandable vermiculite may be expanded by heating in an oven, or incorporated in an intumescent material and heat expanded in situ, or expanded by other heating means. An intumescent sheet is provided which may be used for mounting automotive catalytic converter monoliths comprising an unexpanded vermiculite produced by the method of the invention; an inorganic fibrous material; and a binder.

Availability of interlayer ammonium as related to root vicinity and mineral type.

Abstract: We studied the release of nonexchangeable NH4+ from soils when cropped with ryegrass. The plants were grown in special soil containers in which part of the soil was not in direct contact with the roots. Nonex-changeable NH4+ was released only in the immediate vicinity of the roots where, it is sugge

Analyses of Adsorption Kinetics Using a Stirred-Flow Chamber: II. Potassium-Calcium Exchange on Clay Minerals

Abstract: Potassium-calcium adsorption kinetics on a Llano vermiculite and an Arizona montmorillonite were studied using a stirred-flow technique. Various experiments were conducted to distinguish between (i) instantaneous equilibrium and time-dependent reactions, and (ii) solution-concentration-dependent kinetic models vs. those that are independent of solution concentration. These experiments included varying the flow rate and influent concentration and stopping the flow for a period of time. It was found that K-Ca exchange on montmorillonite was too rapid to be measured with the stirred-flow technique, while exchange rates on vermiculite could be ascertained. Adsorption kinetic parameters should be included in transport models to more accurately predict the fate of ions in soils dominated by vermiculitic and micaceous clay minerals. "DOTASSIUM is AN ESSENTIAL ELEMENT for plant X^ growth and is a dynamic ion in the soil system. Soil K can be divided into four major phases: solution, exchangeable, fixed, and structural (Sparks and Huang, 1985). To fully understand the physical chemistry of soil K and to predict its fate with time, one must have a knowledge of the rates and mechanisms of K reactions. The application of kinetics to soil surface reactions, however, is arduous and has often been limited by the difficulty in separating the solution from the solid phase quickly enough to measure rapid reactions (Sparks, 1989). Also, problems of correctly interpretM.J. Eick and D.L. Sparks, Dep. of Plant and Soil Sciences, Univ. of Delaware, Newark, DE 19717-1303; A. Bar-Tal and S. Feigenbaum, Inst. of Soils and Water, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel. Published with the approval of the Delaware Agric. Exp. Stn. as Miscellaneous Paper no. 1323, Contribution no. 255 of the Dep. of Plant and Soil Sciences, Univ. of Delaware. Received 2 Oct. 1989. 'Corresponding author. Published in Soil Sci. Soc. Am. J. 54:1278-1282 (1990). ing experimental results and comparing different kinetic methods have not been solved. Kinetics of K adsorption on clay minerals have been studied using various methods: batch, stirred batch, vortex batch, and miscible displacement (Keay and Wild, 1961; Jardine and Sparks, 1984; Ogwada and Sparks, 1986). The rate of K adsorption on vermiculite was reported to be much slower than on kaolinite, regardless of the experimental method (Ogwada and Sparks, 1986). Similar results were obtained by Jardine and Sparks (1984), who found K adsorption to be slowest on vermiculite, followed by montmorillonite and kaolinite. Bar-Tal et al. (1990) presented mathematical solutions of the mass-balance equation in combination with equilibrium and kinetic models. They also proposed experimental tests to distinguish between three types of models: (i) instantaneous equilibrium, (ii) kinetic models in which the adsorbed fraction is a function of solution concentration, and (iii) kinetic models in which the adsorbed fraction is independent of the solution concentration. The objective of this study is to determine the utility of different experimental tests (under specific experimental conditions) for distinguishing between kinetic and instantaneous equilibrium processes using a stirred-flow technique for vermiculite and montmorillonite clays. MATERIALS AND METHODS A Llano, Texas, vermiculite and an Arizona montmorillonite obtained from the University of Missouri Source Clays Depository were used in this study. The clays were fractionated by standard procedures (Jackson, 1969), based on a gravimetric method, to an equivalent diameter of 1 to 2 jam. The cation-exchange capacity (CEC) of the Llano vermiculite and the Arizona montmorillonite as determined by Ba-Ca exchange was 210 and 105 cmol kg", respectively. These values are in good agreement with published values (Foster, 1963; Sparks and Jardine, 1984). EICK ET AL.: ANALYSES OF ADSORPTION KINETICS: II. 1279 Prior to the equilibrium and kinetic studies, the clays were made homoionic with respect to Ca by saturating four times with 500 mol nr of Ca(ClO4)2. The excess salt was removed by repeated washing with deionized water until the electrical conductivity (EC) of the supernatant was near that of the deionized water. Complete saturation of the exchanger was tested by replacing the sprbed Ca with Ba. Perchlorate salts were used in both kinetic and equilibrium studies to minimize CaCl* formation (Sposito et al., 1981). Calcium and K concentrations were measured in solution using atomic absorption spectrophotometry.

Clay mineralogy of soils developed on weathered igneous rocks, West Antarctica.

Abstract: Soil samples collected from 33 outcrops of weathered plutonic, hypabyssal, and volcanic rocks scattered along a 1400 km traverse from the West Antarctic coastline to the Polar Plateau were analysed for clay mineral content. Clay minerals present (in approximate order of abundance) are “mica”, chlorite, illite-smectite, smectite, kaolinite and vermiculite. The large amount of “mica” and/or chlorite in almost all host rocks and their associate soils, the small amount of clay (generally < 1%) present in all soils, the weak development of most soil proflles, and the large amount of glass in the clay-sized fraction of soils developed on Tertiary basaltic rocks indicate that physical weathering is the dominant process of weathering in this area. Smectite, vermiculite and illite-smectite are products of chemical weathering. Kaolinite in soils from the Thiel Mountains is unusual, because formation of this mineral is generally thought to require at least moderate amounts of leaching. We feel that kaolinit...

Amphibole alteration to vermiculite in a weathering profile of gabbro-diorite

Abstract: Amphibole weathering to vermiculite in ferromagnesian sandy grains of saprolite and C horizon of a Typic Rhodoxeralf from southern Portugal is studied. Minerals identification and alteration studies were accomplished by X-ray diffraction, optical and electron (scanning and transmission) microscopy and electron microprobe analysis. Vermiculite replaces amphibole along planes which are parallel to the cleavage planes (110) of the primary silicate. In this process the contents of Si, Ca and Mg decrease whereas Fe content remains approximately constant during the initial stage of weathering. On the basis of lattice coherence between a chain silicate and a 2:1 layer silicate, a solid state transformation of amphibole into vermiculite with no intervening non-crystalline phase is proposed.

Surface charge characteristics and clay mineralogy of some variable charge soils in Papua New Guinea.

Abstract: Clay mineralogy and charge characteristics of two lowland volcanic ash soils (Andepts or Andisols) and two strongly weathered soils (Oxisols) have been studied. The clay mineralogy of the Oxisols is strongly related to the composition of the parent material, one profile on ultrabasic rocks being dominated by goethite and the other, developed on basaltic rocks, having kaolinite as the major clay mineral. In contrast, the clay minerals of the soils developed on volcanic ash deposits are dominated by hydroxy Al-interlayered vermiculite which, in one soil, is most likely formed as an alteration product of biotite. In the other profile, however, in the absence of mica, the vermiculite may have formed as an alteration product of feldspars. Charge characteristics for each of the four profiles studied show a characteristic set of curves related to organic matter content, clay mineralogy and exchangeable aluminium at low pH. The results clearly show that organic manuring within the root zone and/or rejuvenation of silica-rich ash showers can be very beneficial in retaining the chemical fertility levels of soils that contain both variable and permanent charge colloids.

Ion Transport in Single Crystals of the Clay-Like Aluminosilicate, Vermiculite

Abstract: We have made an investigation of the ion transport properties of single crystals of the naturally occurring clay vermiculite in order to elucidate the mechanism of conductivity including the predominant charge carrier. Measurements of the ion conductivity, magnetic susceptibility and x-ray lattice parameters of ion-exchanged samples strongly suggest that the native cations and not protons are the major current carriers. We have synthesized the hydrogen form and found that it is a much preferred precursor for ion-exchange by other cations allowing the time necessary for ion-exchange to be reduced from several months to around a week.

Effects of Chlorite Alteration on Uranium Redistribution in Koongarra, Australia

Abstract: The relevance of alteration of chlorite, one of the major constituent minerals of the host rock to uranium ore at Koongarra, to the redistribution of uranium in the vicinity of the ore deposit has been examined. The chlorite alteration is produced by weathering; chlorite is transformed to vermiculite, through regularly interstratified chlorite/vermiculite. The Fe released from chlorite reprecipitates to form iron minerals, possibly ferrihydrite. Vermiculite is then replaced by kaolinite (and possibly smectite), further releasing Fe. On the millimeter scale, an alpha autoradiography study has shown that uranium concentrations are qualitatively proportional to the extent of the alteration; altered chlorite grains having higher uranium concentration. On the meter scale, the X-ray diffraction study has revealed that the abundances of chlorite, vermiculite, and kaolinite correspond well to the low, intermediate, and high uranium concentration zones, respectively. These suggest that the interaction of the uraniferous solution with chlorite causes the alteration of chlorite and the precipitation and sorption of uranium in the alteration products from the solution, and thus, the uranium migration is retarded at Koongarra.

Culture medium for cultivating plant

Abstract: PURPOSE: To obtain the subject new culture medium, having high shape retaining properties with both water absorbing and draining properties and suitable for cultivating tropical orchids, etc., by using peat-moss, vermiculite and a hormite- based mineral as culture medium ingredients, binding the ingredients with PVA and forming the resultant bound ingredients. CONSTITUTION: The objective culture medium is obtained by using peatmoss, vermiculite and a hormite-based mineral as culture medium ingredients, bonding and forming the aforementioned ingredients with PVA. At least one of smoked charcoal, peat, KUROB0KU soil (black soil formed by weathering of volcanic ash, pumice, etc.) and Vinylon(R) fiber is preferably further contained as the culture medium ingredients. Furthermore, the respective dry substance weight ratios of the ingredients to the peat-moss are preferably 0.1-1.5 vermiculite, 0.1-0.5 hormite-based mineral, ≤1.5 smoked charcoal, ≤2.5 peat and/or KUROBOKU soil and ≤0.1 Vinylon(R) fiber. The dry substance weight ratio of the PVA to the aforementioned culture medium ingredients is preferably ≥1.0%. COPYRIGHT: (C)1992,JPO&Japio

Mixed compost for raising seedling

Abstract: PURPOSE:To obtain the subject mixed compost capable of readily realizing suitable nursing conditions by containing rock wool granular fiber in a substrate consisting essentially of clay or a material having physical characteristics comparable to those of the clay. CONSTITUTION:The objective mixed compost obtained by changing the composition ratio according to the species of raised seedlings and adding =50vol% substrate consisting of clay or a material (e.g., containing an additive, such as peat moss or vermiculite in 50vol.% clay) having characteristics comparable to those of the clay.

Cultivation of high mineral rice

Abstract: PURPOSE:To readily obtain high mineral rice by an ordinary culture method by blending black soil with a water absorbing mineral substance, etc., simultaneously culturing Bacillus stearothermophilus, a thermophilic bacterium at high temperature under aeration and using the soil as culture soil. CONSTITUTION:100 pts. wt. black soil [preferably soil collected from mountain land or hill land, soil rich in humus or humic acid or soil containing fowl droppings, pig dung or human feces) is blended with 20-50 pts.wt. water absorbing mineral (preferably pumice, tuff of pumice, Ohya stone, vermiculite, zeolite, etc.) or carbonaceous powder (preferably heavy oil combustion dust, woody fine powder, peat-moss, sphagnum, etc.), simultaneously Bacillus stearothermophilus, a thermophilic bacterium is cultured at relatively high temperature (preferably 40-70 deg.C) under aeration and the soil is used as culture soil to culture high mineral rice.

Nematode-controlling agent and fertilizer

Abstract: PURPOSE:To provide a highly effective nematode-controlling agent and fertilizer non-toxic against human bodies by comprising insolubles which is obtained by treating a micaceous mineral containing various mineral components with a mineral acid and subsequently separating off the effluent. CONSTITUTION:A micaceous mineral such as vermiculite, black mica or calcined vermiculite is mixed or thermally treated with a mineral acid such as sulfuric acid or hydrochloric acid for several hours and the resultant solution is separated off to provide a nematode-controlling agent and fertilizer. The insolubles exhibit remarkable effects for controlling nematodes, highly accelerate the growth of field crops, improve the tastes of the field crops to a higher grade and further is non-toxic against human bodies.

Water resistant vermiculite articles and method of their manufacture

Abstract: A method of rendering water resistant a vermiculite article such as a film or coating comprised of delaminated vermiculite lamellae is provided comprising the step of contacting the article with a solution of an inorganic monovalent cation selected from the group consisting of: H + , Na + , K + , Cs + , Rb + and Fr + and mixtures thereof. The invention further relates to a water resistant article such as a film or coating comprised of delaminated vermiculite lamellae, which article is produced by contacting the article with a solution of an inorganic monovalent cation selected from the group consisting of: H + , Na + , K + , Cs + , Rb + and Fr + .

Heat/flame retardant mixture

Abstract: Perlite spray material can be applied to almost any surface, making that surface/material non-combustible. The material is made up in varying concentrations using the following chemicals: Perlite, vermiculite, water, sodium silicate, methocel (RTM) and cement (added only when ready to use).

Electron Paramagnetic Resonance Studies for Fe2+ ⇌ Fe3+ Reactions in Vermiculite Mineral

Abstract: The oxidation-reduction reactions Fe2+⇌Fe3+ in vermiculite mineral have been studied by the electron paramagnetic resonance technique. The results obtained in a mineral containing essentially Mg2+ and Mg-vermiculite replaced with 0.18% of Pt ion in the interlayer space were compared. It has been shown that oxidation took place during evacuation while reduction occurred in course of H2 treatment.