Iranian Journal of Crystallography and Mineralogy
Year:2004 | Volume:12 | Issue:1|Papers Count:11

In this research we apply X-Ray Fluorescence (XRF) method to determine toxic and heavy metals in stack gases that arises from industrial furnaces. Three factories were selected and various samples were collected from their furnaces and smoke-stacker, and the results compared each other.

for several recent years, syntheses of spherical zeolitic materials, such as S-l, ZSM-5 and Beta, have been reported using an anion exchange resin as macro-templates. Conceptually, these syntheses are based on the use of a colloidal crystal tem plating process. The advantage of this method is preparation of pure self-bonded zeolite micro/macrostructures. In this paper the synthesis of TS-1 is reported using the colloidal crystal tem plating process. The organic template was TPAOH and the resin (IRA900 C1) was used as a macro template. Techniques such as X-ray powder diffraction (XRD), infrared spectroscopy (IR) and optical microscope, were used to characterize synthesized samples.

In this work we have prepared nano-sized Bi-YIG powders, using mechanochemical processing. In this process, a part of the activation energy, which is necessary for chemical reactions, is provided by high-energy mills. The as milled powders obtained by this technique need a lower annealing temperature in comparison with those obtained by conventional ceramic technique to become a single phase garnet. The lower temperature itself can produce ultra fine powders by inhibiting grain growth. The optimum calcining temperature was 800o C for 5 hours milling time, which is much lower than 1000oCneeded in conventional ceramic technique. Longer milling times are not recommended, because it produces extra iron into the powders. The average particle size of the powders was in the range 50 to 60 nm, using Scherer's formula. Room temperature saturation magnetizations of the samples were measured using a vibrating sample magnetometer (VSM). These were 0.022, 6, 17 and 20 emu/g for the samples annealed at 700, 725, 750 and 800o C, respectively. The lower magnetization values respect to the conventional ceramic technique, are discussed according to core-shell model.

In this research the and β phases of hemihydrates have been prepared from Alamout natural gypsum and their setting times have been measured. The IR spectroscopy has been used for characterization of α and β phases of hemihydrates from gypsum. The α and β phases of hemihydrates distinguished from each other by X-ray powder diffraction (XRD). The setting times of pure α and β phases and mixtures of them have been measured by Vicat method. The effects of various additives such as accelerators (NaCl, K2S04, Na2S04) have been studied on setting time. Among them, potassium sulfate had maximum accelerating effect. Optimum concentration of the additive has been determined. This amount is %3 w/w. Less and more than this amount have inverse effects on setting time.

The calc-silicate xenoliths, within the Shir-Kuh batholith are characterized by melilite, garnet, vesuvianite, and wollastonite mineral assemblage. On the basis of paragenetic relations, prograde and retrograde metamorphism are involved in the formation of these minerals. Melilite, wollastonite and diopside formed during progressive metamorphism which was accompanied by thermal peak shocking and decarbonization reactions in pyroxene-hornfels faces. The effect of fluids in later stage, which released during crystallization of batholith, caused the formation of hydrous minerals (hornblende-hornfels facies during retrograding metamoephism.

Considering the importance of micro-structural characteristics of clayey soils on their behavior, the main objective of this research is to investigate the effect of pore fluid properties variations on clayey soils and their physical and micro-structural changes. For experimental purposes, soil electrolyte solutions with the ratio of 1:50 prepared. A series of physical experiments, as well as, SEM and XRD experiments performed to investigate any variation on the soil behavior due to the changes in pore fluid properties. The results of the physical experiments indicate that, with increasing the electrolyte concentration, one will be faced with a change on the soil behavior including its interaction with water. The SEM pictures indicate that with the presence of sodium ions at low concentration, first soil takes a dispersive structure. With a further increase in salt concentration, and due to an increase in attractive forces in comparison with repulsive forces within clay particles, a flocculated structure forms. In addition to the above, during this process, a change will happen on the intensity and basal spacing of clay mineral. It is concluded that the main reason for a noticeable change in physical behavior of soil can be attributed mainly to the significant change in electrostatic forces of clay particles.

This study focused on the upper parts of Karaj Formation in Damavand-Firuzkoh area. Field study indicated that the green tuffites of Karaj Formation in Kilan, Hesarbone, and Zarindasht irregularly altered and changed to zeolite and bentonite. Microscopic studies of zeolitic tuffites have shown that the main components of these tuffites are altered glass shards. The shards changed to zeolites from their margins. In addition to zeolite, clay minerals also changed to glass shards. Scanning Electron Microscopic studies confirmed the change of glass shard to zeolite and clay mineral from their margins. The presence of clinoptilolite and carbonate impurity in vitric altered tuffite are determined by thermal curves tests (TG & DTG). Also, X-ray showed clinoptilolite, crystobalite as major mineral and muscovite, montmorillonite as minor mineral in these tuffites. On the base of XRF and ICP, chemical composition of these tuffites are in the range of acid to intermediate rocks compositions. Chemical composition of altered and unaltered tuffites is unique. Base on the petrological studies, the componential magma of the tuffites is calc alkaline. Spider diagrams indicated the enrichment of K, Ba, Th, Rb, which is characteristic of arc magmatism.

In north of Anarak area, in the upper Proterozoic ophiolite, exist Massive and Vein type Rodingites. Vein type rodingites have fonned in two phases. Massive or Static rodingites have fonned during oceanic crust spreading and ophiolite fonnation, and Vein type or Dynamic rodingites have fonned during Anarak ophiolite emplacement and tectonic activities. Abundance order of minerals in massive rodingites is Garnet (Chromian- Andradite), Idocrase, Chlorite, Diopside, Prehnite and Epidote (decreasing). In the first phase of vein type rodingites, the abundance order of minerals is Diopside, Chlorite, Idocrase, and Garnet (Ti-Andradite), and in the second phase is Diopside, Chlorite and Garnet (Andradite). Petrography and geochemical study of minerals show that, during the fonnation of massive type rodingites, the activity of Calcium, Iron, and Chromium ions in fluids, and during the fonnation of first phase of vein type rodingites, the activity of Calcium, Silicon, Magnesium, Aluminum, Titanium, and OH- ions in fluids, have been increased. Geochemistry of second phase of vein type rodingites is similar to first phase, but because of absence of Idocrase, and low Titanium in Andradite structure, the activity of Iron, Titanium, and Aluminum ions, is lower than first phase. Generally the diversity of minerals in massive type rodingites is more than vein type rodingites.

In this research, Alnico 5DG alloy was melt and cast in the optimum conditions and its samples were homogenised and heat treated in a magnetic field in order to obtain the required magnetic properties. Microstructure, phase composition and magnetic properties of samples were examined in every processing step. The results indicated that the properties of samples were highly influenced by processing parameters. A proper microstructure composed of α1 magnetic phase in a texture of α2 with acceptable magnetic properties was obtained by meticulous control of the processing conditions. The results also revealed that the magnetic coercivity (and remanence) of the cast samples should be increased by an appropriate heat treatment from 12 kA/m (and 0.55 T) to 41.6 Wm (and 1.3 T), respectively.

Different models are discussed to interpret the presence of kyanite as a stable phase in contact aureoles especially in the andalusite-, sillimanite- bearing aureoles. In such aureoles the polymorphic sequence kyanite → andalusite → sillimanite can be explained in tenns of an essentially isobaric path during which kyanite initially crystallises from the breakdown of pyrophyllite or more likely muscovite + chlorite beneath the pressure of the triple point (3-4 kbar 10-14 km depth), followed by andalusite and sillimanite crystallisation. The sequence kyanite-sillimanite and/or fibrolite can be seen in thennal aureoles subjected to isobaric metamorphism above the triple Al2SiO5 point (5-8 kbar 17-28 km depth). The absence of kyanite in some thennal aureoles can be explained on the basis of either compositional constraint or overstepping of low- temperature reactions due to high heating rates.