Showing papers on "Vermiculite published in 1978"

Soil alkalinity. i. equilibria and alkalinity development

Abstract: Summary Theoretical relationships between pH, CO2 partial pressure and alkalinity (bicarbonate + carbonate concentrations) have been shown to apply to solutions and calcite and soil suspensions. The exchange of Na onto three Ca clays shows that Ca is preferred but with negative free energies of exchange. With decreasing total electrolyte concentration, the preference for Ca increases, so that only when the concentration is above 10-3M will significant amounts of exchangeable Na be found in soils. The preference for Ca is illite > montmorillonite > vermiculite. Dilution of the mixed Na-Ca clay suspensions causes exchange, desorption of Na and. in some cases Ca. This desorbed or ‘alkaline’ Na (and Ca) is replaced by H some of which attacks the clays. The apparent hydrolysis coefficient, KG = H adsorbed (Na)/Na adsorbed (H), varies between 5 and 9 × 105, increases with increase in electrolyte concentration and varies in the order vermiculite > illite > montmorillonite. The concentration of alkaline Na + Ca increases with increasing ESP, and with clay type in the same order as the KG values. The pH calculated from the alkaline Na + Ca, assumed equal to the alkalinity was equal to measured values except for montmorillonite where the calculated values were low. Magnesium release by acid attack of the montmorillonite may explain the differences. Vermiculite rich soils will be most likely to accept exchangeable Na and to hydrolyse and develop alkalinity.

Selectivity and adsorption capacity of smectite and vermiculite for aluminum of varying basicity

Abstract: Smectite (from South Dakota, Wyoming, and Mississippi) and Vermiculite (Transvaal) were treated with solutions of Al(OH)B(3-B+), with B varying from 0 to 2.5. The average basicity (OH/Al = B) of the Al adsorbed differed very much from the basicity of the Al added. The average basicity of the Al adsorbed by smectite was always above the average basicity of the Al added. In contrast to smectite, Vermiculite adsorbed smaller hydroxy-Al complexes. One reason for the different selective behavior was the difference in expansion between smectite (about 18 A) and vermiculite (about 14 A). Because of the adsorption of the relatively more basic OH-Al by smectite, smectite adsorbed considerably more Al than vermiculite. The total amount of aluminum in the interlayer generally could not be calculated by the difference between Al added and that remaining in solution after the reaction because of possible protonation of the clay mineral and adsorption of structural Al and other cations, which is more pronounced for vermiculite. The results in the present study demonstrated that neither the quantitative nor the qualitative composition of an Al(OH)B-treated exchanger can be deduced from B of the Al salts added. These points are frequently overlooked when cation exchangers are pretreated with Al of variable basicity and are used for further investigations, such as studies of CEC, surface area, interlayer spacing, anion reactions, the formation of gibbsite, etc. Before these kinds of investigations are conducted employing the pretreated OH-Al-exchangers, their composition should be known precisely.

The reaction of ammonia with vermiculite and hydrobiotite

Abstract: The reaction of ammonia with Mg-saturated vermiculite and hydrobiotite was studied by chemical analysis, X-ray diffraction, and differential thermal analysis, and the hydrobiotite also by infrared spectroscopy. The experimental evidence indicates that ammonia is adsorbed mainly as the ammonium ion, formed partly by reaction with inter- layer water and partly by reaction with protons dissociated from octahedral layer hydroxyl groups, giving a single sheet of ions and molecules with irregular interlayer spacing. With large flakes (0"5-1.0 ram) the adsorbed ammonia is strongly retained on heating or on rehydration with water vapour: smaller flakes lose ammonia more readily. Ammonia uptake is related quantitatively to cation exchange capacity with two vermiculites and three hydrobiotites, and to the water content prior to adsorption. Na-saturated vermiculite adsorbs a similar amount of ammonia to the Mg form, but it is mostly desorbed on rehydration. Cu-saturated vermiculite displays intermediate behaviour, with much of the ammonia initially present as a Cu-ammine which slowly reacts to give more ammonium ion.

Method of separating vermiculite from the associated gangue

Abstract: A method of separating vermiculite from the associated gangue is disclosed in which the ore is fed to the top of a rotating support comprising a grounded conductive underlayer and a nonconductive overlayer and the ore particles are pinned to the rotating support by ion bombardment. The gangue tends to separate first from the roll while the vermiculite particles have a greater tendency to remain pinned to the roll and can be collected as a separate fraction.

Water on the Surfaces of Clay Minerals: Orientation, Diffusion and Proton Exchange

Abstract: The surface of clay minerals such as montmorillonite and vermiculite offersan unique environment for the study of water molecules arrangement and of their interaction with cations since

Composition and process for a granular plant nutrient

Abstract: Granular, free-flowing, slow release plant nutrient compositions suitable for use in growth media are prepared by treating granules of a calcined clay, such as montmorillonite, attapulgite, sepiolite chlorite or vermiculite, with one or more solutions of salts of iron, boron, molybdenum, chloride, manganese, zinc, copper and sulphur. Optionally, the salt solutions may contain a sequestering agent.

Building elements and their preparation

Abstract: An improved building material element or board having good thermal insulation properties comprising expanded vermiculite granules coated with 2 to 30% by weight, based on the weight of vermiculite, with an organic binder formed into a press cake which is then press heated to form the building element, the improvement comprising that at least a portion of the coated vermiculite granules are recycled particles which increases the density and has a more uniform and more easily sized surface and a process for its preparation.

Soil activator and its preparation

Abstract: PURPOSE: To obtain the title product useful for fertilization of soil, by adsorbing a culture of microorganisms to decompose and decay organic matter in soil and a specific substance necessary for them on vermiculite powder and calcium carbonate rock powder. CONSTITUTION: (A) A culture of microorganisms, e.g. thermophlic fibrinolytic bacteria, actinomycetes (ray fungi), molds and yeasts, photosynthetic bactera, or heterotrophic bactera, useful for decomposition and decay of organic matter in soil as seed bacteria, in a medium and (B) a specific organic nitrogen source, vitamins, minor nutrients, and growth factors are adsorbed on (C) a mixture of vermiculite and calcium carbonate rock powder to give a soil activator. EFFECT: High porosity, water and base retention improve the acid soil. COPYRIGHT: (C)1980,JPO&Japio

Absorbent litter for animal e.g. cat excrement - consisting of vermiculite with specified bulk density and particle size

Abstract: New absorbent for animal excrement consists of vermiculite with a bulk density of 200 g./l. (pref. 100 g./l.), and a granule size of not >15 mm. (pref. 3-6 mm.). A disinfectant is pref. admixed with the vermiculite, generally in an amt. of ca. 0.1-5% w/v. A pref. disinfectant is benzalkonium chloride. The material is for use as litter for spreading on the floor of the cages etc. of domestic animals (e.g. cats, hamsters) so that the animals' excrement can be disposed of in a hydienic manner. Vermiculite with the specified bulk density and particle size is lighter than conventional litter materials and has a higher absorption capacity. Addivitives (e.g. disinfectants) are readily mixed with the vermiculite. Individual vermiculite particles are soft in consistency, being readily accepted by animals, and are dust free.