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Efektet e trajtimit termik të tokës diatomike nga Mariova në intervalin 500-1200°C
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The diatomaceous earth (DE), collected from the Mariovo region in North Macedonia, was characterized and thermally modified. The material represents a sedimentary rock of biogenic origin, soft solid that can be easily disintegrated, with white to grayish color, with bulk density of 0.51–0.55 g/cm3, total porosity of 61–63%, and specific gravity of 2.25 g/cm3. The chemical composition is as follows: SiO2, 86.03; Al2O3, 3.01; Fe2O3, 2.89; MnO, 0.06; TiO2, 0.20; CaO, 0.76; MgO, 0.28; K2O, 0.69; Na2O, 0.19; P2O5, 0.15; and loss of ignition, 5.66 (wt%). The mineralogy of the raw DE is characterized by the predominant presence of amorphous phase, followed by crystalline quartz, muscovite, kaolinite, and feldspar. Significant changes in the opal phase are observed in the 1,000–1,200°C temperature region. At 1,100°C, the entire opal underwent solid–solid transition to cristobalite. Further ramp of the temperature (1,100–1,200°C) induced formation of mullite. Scanning electron microscopy (SEM) and transmission electron microscopy depict the presence of micro- and nanostructures with pores varying from 260 to 650 nm. SEM analysis further determined morphological changes in terms of the pore diameters shrinkage to 120–250 nm in comparison to the larger pores found in the initial material. The results from this investigation improve the understanding of mechanism of silica phase transition and the relevant phase alterations that took place in DE upon calcination temperatures from 500 to 1,200°C.
Trepel is the local name for a mixture of diatomaceous earth and clay minerals. It represents a greyish, soft, very light, weakly cemented, fine biogenetic sedimentary rock. The studied material is taken from the vicinity of Bitola city (Republic of Macedonia). Here, trepel was treated up to three temperature intervals (800, 1000 and 1200 C) for a period of 1 hour. The X-ray powder diffraction results indicate the presence of both an amorphous phase and the following crystalline phases: quartz, feldspars (plagioclase), mica (muscovite) and chlorites. The results of SEM analysis revealed skeletons of alga Diatomeae with nano-pores. By thermal treatment of the samples, a gradual change in color as well as higher bulk density and compressive strength was observed. The increase of the temperature, in addition, affected the mineralogical composition and increased the presence of the amorphous phase (aluminasilicate glassy phase). SEM results of the thermally investigated samples depicted morphological changes expressed by shrinkage of the pore diameters in comparison to the initial material. The major and minor constituents were established by chemical analysis revealing the following chemical composition of raw trepel: SiO 2 (63.65 wt%), Al 2 O 3 (11.76 wt%), Fe 2 O 3 (5.93 wt%), MnO (0.13 wt%), TiO 2 (0.63 wt%), CaO (1.42 wt%), MgO (2.22 wt%), P 2 O 5 (0.11 wt%), K 2 O (1.63 wt%), Na 2 O (0.92 wt%), LOI (11.50 wt%).
The physico-mechanical, chemical and mineralogical characteristics of volcanic glass (perlite)
from the Mariovo region (Macedonia) as well as the mineralogical changes that occur during its
thermal treatment were investigated to demonstrate its utilization for industrial use. The native
perlite was characterized by chemical analysis, X-ray powder diffraction (XRPD), infrared (IR)
spectroscopy, thermal analysis (TGA/DTA), scanning electron microscopy (SEM-EDX), transmission
electron microscopy (TEM), and solid- state NMR. The chemical examination suggests that
the perlite represents an acidic volcanic rock with a high percentage of SiO2 (72.45%), high in alkali
metal oxides (4.21 wt.% K2O, 3.56 wt.% Na2O), with a loss of ignition 3.54 wt.%. Results from
the XRPD indicated major amorphous behaviour, with low amounts of feldspars, quartz, and cristobalite.
SEM examinations revealed glassy structure with presence of certain pores (dimensions
ranging from 50–100 μm). The determined expansion coefficient was 20 times its original volume.
XRPD of expanded perlite compared to the native perlite depicted new intensive peaks of cristobalite.
SEM and TEM revealed irregular morphology with broken or ragged edges. On the basis
of the chemical and mineralogical composition, the studied perlite is classified as an appropriate
material suitable as ceramic flux to lower the sintering temperature.
The following document presents a concise description of the transmission electron microscopy technique, which is an application used for the analysis and visualization of samples that are in the order of micrometers and Nano-meters. This technique uses the emission of electron beams as the fundamental basis of its operation, unlike the optical microscope which uses photon radiation, this technique allows to have high-resolution images focusing high energy electrons, in this paper are presented the functioning and the main characteristics of the transmission electron microscope (TEM) along with its limitations and applications.
In the present study, definition of scanning electron microscopy (SEM) was presented in terms of the main component of the instrument and step-by-step the process of SEM system. Schematic drawings with SEM components pictures were provided for understanding the procedure of work in easy and true way. Also, types of SEM were presented and discussed. The capability of energy-dispersive spectrometer (EDS) was also presented; this included historical background of EDS and how it works in accordance with SEM. The existence of EDS capability with SEM instrument is very essential for qualitative and quantitative analysis for any specimen. In the absence of EDS only information on surface topography of the specimen can be produced through SEM. The two most powerful features of SEM image are introduced and discussed namely secondary electron imaging and backscattered electron imaging. Understanding principle of work of both features is very important to have a complete knowledge on how SEM instrument works. SEM is characterized by its easy operation. Having that knowledge one can manage to perform the analysis and imaging very smoothly.
Burial of radioactive waste is an urgent contemporary problem. The development of materials for the disposal of radioactive waste is also topical. In this paper, we consider the possibility of using mica to solve these problems. Mica has been known for a long time and studied by researchers from almost all countries of the world. The areas of its use are constantly expanding and renewing. Mica has high electrical insulation properties. Because of this, the field of application of mica was the electrotechnical industry for a long time. Currently, the range of using mica is quite wide. In this paper, attention is paid to the relatively promising areas of its use. The possibility of using composite materials based on mica as materials for protection against radioactive emissions and disposal of radioactive waste is considered. The object of the study: samples of a composite material based on mica, or the mikalexs. The method of recording ionizing radiation and the mass spectroscopic method were used to study linear coefficients of μ attenuation from gamma radiation of mikalexes on the basis of various micas after bombardment with 5 MeV, 10 MeV, 25 MeV electron beams. We used: a cesium source of γ-radiation with E = 0.661 MeV and a cobalt source with E = 1.25 MeV. Research results on the μ linear attenuation coefficients on γ-radiation of mikalexes based on various micas after their bombardment with electron fluxes showed that electron bombardment increases the penetrating power of gamma radiation in the mikalex. The dependence of the coefficient of linear attenuation on the type of mica used was determined. A new field of use of composite materials based on mica (micalex) for radiation protection and the disposal of radiation waste and their use in ultrahigh vacuum.
In this paper, we systematically report the synthesis of nano silica powder from natural silica sand by a continuous process. Extraction of sodium silicate from silica sand was through a hydrothermal process, then sodium silicate was ready to be used as a precursor in the form of silicate slurry by coprecipitation process. The silicate slurry of SiO2.XH2O was then dried in a furnace at 150 °C for 4 hours until obtaining a pure white SiO2 powder. At a calcination temperature of 900 °C, the sample was then tested by XRD to analyze the transformation of the crystal phase of SiO2 nanoparticles. Identification of functional group absorption was undertaken by FTIR test, and the particle grain microstructure was analyzed by SEM. At calcination temperature of 900 °C, the SiO2 silica nanoparticles experienced a change of phase from amorphous to crystal or amorphous-cristobalite phase; a shift in stiffness for positions of functional group absorption of Si-O stretching or LO functional groups, Si-O stretching or TO, Si-O-Si bending and Si-O-Si rocking and OH-functional groups occurred; the growth of particle grains happened with a spherical and oval trend, with a larger size. SiO2 nanoparticles were successfully synthesized by a continuous method and 900 °C calcination temperature had a significant effect on structural phase changes, the formation of siloxane functional groups, silanol, and grain growth on SiO2 nanoparticles.
Quartz is found in almost every geological environment. It is a common constituent in most of the rock types and soil groups. Granite, sandstone, limestone, and most of the igneous, sedimentary, and metamorphic rocks contain quartz. Quartz contains mainly oxygen and silicon. These two constituents make upto 75 % of the earth’s crust. An alternate name for the Quartz Group is the Silica Group. In this report, the following aspects of quartz are highlighted:
1. Importance and uniqueness of quartz
2. Physical, chemical and optical properties
3. Varieties of quartz
4. Occurrence and crystallization of quartz
5. Uses of quartz.
Removing hexavalent chromium from contaminated wastewater is very important because of toxicity to living organisms. Chromium is carcinogenic and mutagenic in very low concentration values (sub-ppm). The ability of the natural mineral (bentonite) for adsorption of hexavalent chromium, Cr(VI), from aqueous solutions was investigated. The influence of different physical and physicochemical parameters (pH, amount of adsorbent, adsorbate initial concentration) was examined. For characterisation of adsorbent, classical chemical analysis thermo-gravimetric analysis (DTA/ TGA), XRD analysis, FTIR-analysis and determination of specific surface area by BET were performed. For quantitative monitoring of the dynamics of studied system for the presence of Cr(VI) ions in model solutions, the AAS and UV/ Vis analysis were used. The obtained experimental results were used for modelling of the equilibrium of the process through the application of software package MATLAB/Curve Fitting Toolbox., Following adsorption isotherms: Lang-muir, Freundlich, Langmuir-Freundlich and Redlich-Peterson, are applied for analysing the equilibrium of adsorption system Cr(VI) ions – bentonite.
Kaolin has been identified as a very important group of clay mineral, which is copiously utilized as an
industrial mineral commodity. The various physical attributes of kaolin mineral have made it useful in various
ways industrially and these include paints, ceramics, rubber, paper, petroleum and glass industries. Kaolin is often used in soap production as a filler, which facilitates the structure and riser attribute of the soap. In this research, nine samples were collected from three different companies in Aba (South
-Eastern Nigeria). The samples were analyzed to determine their suitability for soap production.
Their physical properties such as particle size, moisture content, shrinkage, grit and viscosity were evaluated. The results show that all samples were fine and ranges from well-graded to uniformly-graded kaolin samples, with low moisture content (0.5% to 1.9%), low shrinkage (4.3% to 11.4%), low grit (0.4% to 3%) and high efflux time (37 secs to 58 secs)
The article discusses possibilities for creating sustainable concrete compositions from local dolomite raw materials. In the first part of the article, practical examples of the use of dolomite quarry by-products (siftings) as a component of concrete mixes are summarized. The second part of article presents experimental study on obtaining caustic dolomite. This method allows obtaining the product with higher added value. Local dolomite raw materials are used and appropriate regimes of thermal treatment have been tested.
Industrial minerals and rocks are Earth materials utilized because of their characteristic physical and/or chemical properties and not because of their metal content and which are not energy sources. According to this definition they cover a broad spectrum of minerals and rocks which form at all geological environments. The relative importance of industrial minerals to the economy of the various countries reflects the economic maturity of that country and today they constitute the most important raw materials exploited in the developed industrialized countries. The unit value of many industrial minerals is small compared to that of metals and depends on the geographic site from which they are extracted, i.e. they have a large place value. The small unit value also dictates the extent of processing and beneficiation. As they are used by the industry because of their physical and chemical properties, different industrial minerals may often compete for the same applications. In some cases the industrial practice requires production of synthetic industrial minerals, such as zeolites and diamonds, with tailored properties and therefore high added value. Due to increasing environmental awareness, there is need for utilization of waste materials from mining activities, which are also in the mineral form and can thus be considered as industrial minerals. The economic significance of industrial minerals is expected to increase further in the future. © 2011 the European Mineralogical Union and the Mineralogical Society of Great Britain & Ireland.
A b s t r a c t: The phase transformations of the amorphous SiO2 have a very important role in the application of diatomite in the production of ceramic products. Therefore the phase transformations of diatomite are observed with the use of DTA and TGA at temperatures up to 1100°C, and diatomite in powder state heated at temperature 1000–1200°C for a period of 1 and 2 hours. DTA and TGA analyzis show that during thermal treatment up to 1100°C the diatomite remains in its amorphous phase. Roentgen-structural examinations of probes heated at 1000–1200°C for a period of 1–2 hours show no presence of crystalline phases at 1100°C. XRD examinations of probes heated at 1200°C show presence of the crystalline phases cristobalite and quartz. The samples was heated at 1200°C for a period of 2 hours, and was observed with an increase of the cristobalite content compared with quartz. SEM and TEM examinations results of diatomite heated at 1200°C for a period of 2 hours show that the probes undergoes sintering followed by reduced porosity.
For the characterization of the natural amorphous SiO2 found in a new deposit in Republic of Macedonia, the following examinations were performed: physical-mechanical, chemical, mineralogical, SEM, IR and thermal examinations. Physical-mechanical analyses show that it is a white to grey colored rock, of low hardness, with a low volumetric mass and high porosity. Chemical analyses show that the material dominantly contains SiO2. Mineralogical and XRD analyses show high percentage of isotropic amorphous mass content, with minimal contents of submicroscopic cryptocrystalline mass. Thermal analyses show high thermal stability. Based on the conducted research of the raw material from the new deposit, it can be concluded that it represents SiO2-diatomite of high quality, useful for various purposes.
Key words: amorphous SiO2; diatomite; thermal analysis; chemical analysis; XRD analysis; optical microscopy;
SEM analysis
The aim of this paper is to present the physic-mechanical, chemical and mineralogical-petrographic examinations of the pumice and trepel. The pumice is
from deposit site called Bojanciste, near Kavadarci, and the trepel deposit is from Suvodol near Bitola, Republic of Macedonia. The mineralogical-petrographic
examinations of the pumice and pumicite have shown that the main component of the pumice and pumicite it is the volcanic glass, while in the crystal phase there is
presence of albit, oligoclass, anorthit, microklin and in small quantities presence of quartz, biotit and augit. The examinations of the trepel have shown that it is a
sedimentary rock (of biogenic origin) with greyish-white colour, very light and soft, porous and with fine to superfine grained structure. The trepel is composed mainly of
opal as well as quartz, feldspar, illite and chlorites.
Local refractive index changes are the building blocks of ultrafast laser-induced optical functions in bulk transparent materials for photonic applications. The use of a fused silica as a target material plays a paramount role, that was the subject of my research.
Depending on the regime of laser interaction ultra-short pulses can induce either positive isotropic index changes or produce self-arranged nanoscale layered periodic structures resulting in form birefringence. By controlling of the energetic dose, pulse duration and focusing conditions, user-designed selection between the isotropic and birefringent traces could be performed, tuning the optical properties from low-loss waveguides to polarization and phase retardation functions. To this end, complex polarization sensitive devices were designed and fabricated.
One major issue of my work is the mesoscopic scale electronic structural transitions associated with these index forms. As these types of refractive index changes have consequences in the functionality and the performances of embedded optical devices, an investigation of the laser-induced structures is particularly useful. Applying spatially-resolved photoluminescence and Raman microscopy investigaton of defect formation and redistribution can be performed, and, thus, glass network reorganization paths can be determined.
Dolomite is not a simple mineral; it can form as a primary precipitate, a diagenetic replacement, or as a hydrothermal/metamorphic phase, all that it requires is permeability, a mechanism that facilitates fluid flow, and a sufficient supply of magnesium. Dolomite can form in lakes, on or beneath the shallow seafloor, in zones of brine reflux, and in early to late burial settings. It may form from seawater, from continental waters, from the mixing of basinal brines, the mixing of hypersaline brine with seawater, or the mixing of seawater with meteoric water, or via the cooling of basinal brines. Bacterial metabolism may aid the process of precipitation in settings where sulfate-reducing species flourish and microbial action may control primary precipitation in some hypersaline anoxic lake settings.
The clayey diatomite from the village of Suvodol (Bitola region) used in this research has shown to be a very effective and efficient natural material for the removal of Cr(VI) ions from aqueous solutions. The adsorption of Cr(VI) ions onto a clayey diatomite was shown to occur very efficiently with 96.7%. During the experiments the effect of operating parameters, such as amount of adsorbent (0.5–5.5 g/l), initial adsorbate concentration (0.3, 0.4, 0.5, and 0.6 mg/l), and time of adsorption (5–180 min) at pH of the solution 3, was examined. It was found that 2.5 g/l is optimal adsorbent dosage for maximal removal of Cr(VI) ions. Atomic absorption spectrophotometric (AAC) method and UV-Vis spectrophotometric analysis are used for quantitative monitoring of the dynamics of the studied system regarding the presence of Cr(VI) ions in the model solutions. The effect of the initial concentration and quantity of adsorbent is examined, in order to determine the conditions that enable maximum removal of Cr(VI) ions with clayey diatomite. For the purpose of modeling the equilibrium, the kinetics, and dynamics of the tested system of the process of elimination of Cr(VI) ions with the raw material in different operating conditions, MATLAB/Curve Fitting Toolbox was conducted.
The aim of this study was to test the diatomaceous earth from a deposit near Rožden Village (Macedonia) as a raw material for low temperature hydrothermal production of porous ceramics. Hydrothermal synthesis of porous ceramics has been carried out under saturated steam pressure at 130 °C for a period of 1, 2 and 3 hours. The objective of this work was to investigate the impact of slaked lime, autoclave curing time, autoclaving temperature and compaction pressure on the compressive strength and porosity of the products. During the hydrothermal synthesis, newly obtained calcium silicate hydrate dominates which give positive effect to the compressive strength and product porosity confirmed by X-ray powder diffraction. Moreover, a calcite was also evidenced by FTIR spectroscopy whose presence additionally increases the compressive strength of the hydrothermal products. The products obtained during the low-temperature hydrothermal reaction are classified as light porous ceramics with bulk density ranging from 0.71–0.91 g/cm³ and compressive strength within 14.7–19.4 MPa.
This U.S. Bureau of Mines paper discusses the structure of the talc industry, talc production, processing of talc ore, applications and demand for talc, and the outlook for the talc industry. In recent years, U.S. demand for talc has slowed considerably. The average annual growth in demand was 3.1% between 1967 and 1977. Between 1977 and 1987, the average annual growth in demand was slightly negative. Demand, however, averaged approximately 930,000 st/yr for this period. Relative increases and decreases in demand have been the result of minor market fluctuations rather than long-term trends. Demand for talc is expected to continue to fluctuate around 930,000 st/yr in the near future. The major U.S. demand for talc will continue to be by the ceramics industry, which will account for 30% to 35% of the total demand. Demand by the paint industry, if it continues to follow its 10-yr downward trend, will drop below that of the paper industry in several years. The use of talc by the paper industry should continue to increase as paper consumption grows. Demand by the plastics industry should grow slightly, following a large decline in the early 1980's.
Industrial minerals include both common and uncommon minerals and some rocks. Construction raw materials such as aggregates are included. Industrial minerals can be categorized according to their market characteristics as bulk minerals, either within or outside a vertically integrated industry, national or regional commodities, internationally traded commodities, dual-purpose metal ores, or very high-value minerals. Bulk minerals are almost entirely used for construction. National and regional commodities in general supply the needs of basic industries in a country. Internationally traded commodities are less widespread. They are often marketed through an industrial minerals trader, with no direct relationship between the producer and consumer. A broad correlation can be established between the industrial mineral categories and the terrain in which they can be found. A passive continental margin with a sequence of sedimentary rocks can contain many of the industrial minerals used as national or regional commodities. Many bulk minerals are also found here. Internationally traded commodities tend to be found in either basement strata, active continental margins or in rift-valley terrains. Weathering processes lead to further industrial minerals found either as residual or alluvial and placer deposits. © opyright 2011 the European Mineralogical Union and the Mineralogical Society of Great Britain&Ireland.
Diatomite in its natural form possesses low reactivity and is a weak material. Calcination rids of the burnable elements and enhances the properties of diatomite. This research studies the properties of pressed lightweight concrete containing calcined diatomite aggregate. The diatomite was crushed and classified as fine, medium and coarse aggregates and then calcined at 400–1000 °C for 4 h. The pressed lightweight concretes with 28-day compressive strength of 7.8–12.9 MPa, density of 1000–1200 kg/m3, porosity of 58–61%, water absorption of 61–72% and thermal conductivity of 0.15–0.19 W/mK were obtained. The light weight and high strength blocks were obtained with the use coarse diatomite aggregate obtained from high calcined temperature of 1000 °C and the use of fine diatomite aggregate obtained from calcination temperature of 600 °C. At the high temperature of 1000 °C, the coarse aggregate was stable and strong and this contributed to the strength of the pressed lightweight concrete. At the calcination temperature of 600 °C, the fine diatiomite aggregate was reactive. Calcined diatomite is a suitable lightweight aggregate for making pressed lightweight concrete blocks.
In this paper, adsorption isotherm of urokinase on two typical local diatomites were determined at 25°C and their surface electrical potentials (ζ), isoelectrical point values (IEP) were determined. The properties of diatomites, the relationship among diatomite structure, pore-size distribution, surface ζ and adsorption isotherm were discussed. The adsorption equation of urokinase was calculated from the adsorption isotherm. The adsorption mode of urokinase on diatomite surface was judged by the configuration function α. The relationship between the amount of adsorbed urokinase and IEP value was also discussed.
This paper deals with the preparation, characterization, and determination of thermal energy storage properties of polyethylene glycol (PEG)/diatomite composite as a novel form-stable composite phase change material (PCM). The composite PCM was prepared by incorporating PEG in the pores of diatomite. The PEG could be retained by 50wt% into pores of the diatomite without the leakage of melted PEG from the composite. The composite PCM was characterized by using SEM and FT-IR analysis technique. Thermal properties of the composite PCM were determined by DSC analysis. DSC results showed that the melting temperature and latent heat of the composite PCM are 27.70°C and 87.09J/g, respectively. Thermal cycling test was conducted to determine the thermal reliability of the composite PCM and the results showed that the composite PCM had good thermal reliability and chemical stability. TG analysis showed that the impregnated PEG into the diatomite had good thermal stability. Thermal conductivity of the composite PCM was improved by adding expanded graphite in different mass fractions. Thermal energy storage performance of the composite PCM was also tested.
Adsorption experiments were performed under batch process, using Th(IV) initial concentration, pH of solution, contact time and temperature as variables. Th(IV) uptake by calcined (C-D) and flux calcined diatomite (FC-D) was pH dependent (pH range, 3.0–6.0) and maximum sorption was observed at pH 4.0. Sorption capacities for Th(IV) were found to be 0.52 (121.22 mg Th/g) and 0.50 mmol/g (116.69 mg Th/g) for calcined diatomite (C-D) and flux calcined diatomite (FC-D), respectively. Adsorption process is well described by Freundlich and Dubinin–Radushkevich (D-R) isotherms in comparison with Langmuir, Temkin and Flory–Huggins isotherms. Thermodynamic data (ΔH°, ΔS°, ΔG°) were calculated from the temperature-dependent sorption isotherms. Results suggested that the adsorption of Th(IV) on calcined and flux calcined diatomite was a spontaneous and endothermic process. A comparison of kinetic models applied to the adsorption of Th(IV) onto C-D and FC-D was evaluated for the pseudo-first-order, pseudo-second-order, intraparticle diffusion and film diffusion kinetic models. The experimental data fitted very well the pseudo-second-order kinetic model and also followed by intra-particle diffusion model, whereas intraparticle diffusion and film diffusion are both the rate limiting steps for Th(IV) onto calcined and flux calcined diatomite.
Diatomite is a pozzolanic material containing amorphous silica, cristabolite and minor amounts of residual minerals. Waste marble powder (WMP) is an inert material which is obtained as an industrial by product during sawing, shaping, and polishing of marble and causes a serious environmental problem. This paper describes the procedures and results of a laboratory investigation of mechanical properties carried out on the concrete specimens containing diatomite and WMP as partial replacement of cement in concrete. The laboratory work essentially consists of characterization of the raw and waste materials, preparation of concrete specimens with diatomite and WPM in different ratios by weight as replacement for cement and a superplasticizing admixture to reduce water demand and compression and flexural tests of the specimens. Test results indicated that the concrete specimens containing 10% diatomite, 5% WPM and 5% WPM +10% diatomite replacement by weight for cement had the best compressive and flexural strength and the replacement of cement with diatomite and WMP separately and together using a superplasticizing admixture could be utilized to improve the mechanical properties of the conventional concrete mixtures.
Laboratory tests were carried out to examine the insecticidal effect of three commercially available diatomaceous earth (DE) formulations on wheat and maize against three major stored-grain beetle species: Rhyzopertha dominica, Sitophilus oryzae, and Tribolium confusum. The three DEs tested were Insecto®, PyriSec®, and Protect-It®. These DEs were applied alone or in all possible combinations (Insecto®+PyriSec®, Insecto®+Protect-It®, PyriSec®+Protect-It®, and all three DEs together), at three (total) dose rates: 0.25, 0.5, and 0.75 g/kg of each commodity. Adults of the above species were exposed to the treated commodities for 7 d at 26 °C, and 65% r.h., and after this interval the mortality was measured. For each species, adult mortality was significantly affected by the type of DE, the commodity, and the dose rate. All DEs were less effective against T. confusum, where mortality did not exceed 67%, in comparison with the other two species, where 100% mortality was achieved in some combinations. For all species tested, all DEs were more effective on wheat than on maize. Generally, the mix of two or three DEs was more effective than the application of one DE, for all species and commodities. The results of the present work clearly indicate that a blending of several DEs together may produce a new DE formulation that is highly effective at low dose rates.
Two major deposits of diatomaceous earth (diatomite) in the region of the Balkan Peninsula, the Kolubara basin (Serbia and Montenegro) and the Vesje deposit (Former Yugoslav Republic of Macedonia), were selected for detailed investigation of their possible application in preparation of beer filter aids. Chemical, mineralogical and structural properties of diatomite samples were analyzed with the aim of predicting the filtration efficiency. Results of beer filtering compounds preparation are presented in this paper. The parameters of crushing, drying, calcination and classification are also defined. Beer filtration tests proved diatomites to be satisfactory and not causing any degradation of filtration process or beer quality. Technological flow scheme for obtaining the beer filter aids is proposed in the paper.
A critical step in quantifying the amount of crystalline silica in mineral deposits is the accurate identification of all mineral constituents. It is particularly important to correctly identify the low-temperature opaline silica polymorphs opal-C and opal-CT which, depending on degree of ordering, can be mistaken for α-cristobalite in standard x-ray diffraction patterns. Misidentification occurs because there is limited x-ray diffraction data available from the literature and because these minerals have diffraction maxima that coincide with those of high temperature cristobalite, X-ray diffraction patterns of opal have been collected in 20 bentonite, fuller's earth, and diatomaceous earth deposits to illustrate the range in ordering that naturally occurs in these polymorphs. Two opaline silica polymorphs are commonly observed. Opal-C is characterized by sharp, intense (101) reflections centered near 4.0 Å with peak widths ranging from 0.222 to 0.453 Å and opal-CT is characterized by broader, less intense (101) reflections centered near 4.07 to 4.10 Å with peak widths ranging from 0.506 to 0.883 Å. Opal-A was observed in one sample. Opal-A is easily distinguished from the other opaline silica polymorphs and from α-cristobalite using x-ray diffraction. Opal-C and opal-CT, however, are not as readily distinguished from α-cristobalite. The position and width of the (101) peak can be used to distinguish these polymorphs from one another or a simple heating test can be used. Because opaline silica is hydrated, the position of the (101) reflection shifts and sharpens as a result of heating When α-cristobalite is heated to change in peak position is observed. It has also been found that opaline silica, when reacted with phosphoric acid, potassium pyrosulfate, and sodium sulfide solutions, is considerably more chemically reactive than the crystalline silica minerals. Based on results of the heating test and the position and width of the 4 Å peak of the unheated sample, none of the 20 bentonite, fuller's earths, or diatomaceous earth deposits analyzed contain high temperature α-cristobalite.
The removal of BTEX (benzene, toluene, ethyl-benzene and m-,p-,o-xylenes), MTBE (methyl tertiary butyl ether) and TAME (tertiary amyl methyl ether) from aqueous solutions by raw, thermally, chemically and both chemically and thermally treated diatomite was studied, through batch adsorption experiments. In total, 14 different diatomite samples were created and tested. Selected physical characteristics of the adsorbents, such as specific surface area and pore volume distribution, were determined. Matrix and competitive adsorption effects were also explored. It was proved that the diatomite samples were effective in removing BTEX, MTBE and TAME from aqueous solutions, with the sample treated with HCl being the most effective, as far as its adsorption capacity and equilibrium time are concerned. Among the contaminants, BTEX appeared to have the strongest affinity, based on mass uptake by the diatomite samples. Matrix effects were proved to be strong, significantly decreasing the adsorption of the contaminants onto diatomite. The kinetics data proved a closer fit to the pseudo second order model, while the isotherm experimental data were a better fit to the Freundlich model. However, the latter produced values of the isotherm constant 1/n greater than one, indicating unfavorable adsorption.
The inherent or enhanced solid acidity of raw or activated diatomite is found to have significant effects on the synthesis of hierarchically porous diatomite-templated carbon with high surface area and special porous structure. The solid acidity makes raw/activated diatomite a catalyst for the generation of porous carbon, and the porous parameters of the carbon products are strongly dependent on the solid acidity of diatomite templates. The morphology of diatomite also dramatically affects the textural structure of porous carbon. Two types of macroporous structures in the carbon product, the partially solid pillars and the ordered hollow tubes, derive from the replication of the central and the edge pores of diatom shell, respectively. The hierarchically porous carbon shows good capability for the adsorption of solvent naphtha and H(2), enabling potential applications in adsorption and gas storage.
The introductory chapters deal with classification, genesis, form and size of industrial raw material deposits and include a tabulated survey of genetic types of industrial minerals and rocks. The bulk of the book concerns the characteristics, uses, genetic types and production of 48 commodities under the headings industrial minerals, industrial rocks and building raw materials. There is also a chapter on non-traditional raw materials. Subsequent chapters cover minerogenetic provinces and epochs, methods of prospecting, laboratory investigation, mining and dressing methods. Finally there is a discussion of recent and anticipated future significance of industrial minerals and rocks in world economics. -M.J.Bennell-Baker
The Pd nanoparticles immobilized on natural diatomite were achieved by a simple procedure. The catalysts are highly active for Heck and Suzuki reactions and can be recovered and reused many times. The catalytic process was also investigated.
Room temperature vulcanizing (RTV) silicone foams are commonly used for compression sealing, structural support, packaging, and damping applications. The presence of sorbed water in foams can affect the mechanical and chemical properties of these materials. In order to investigate water sorption behavior, a silicone foam containing diatomaceous earth filler was synthesized and studied for water uptake characteristics at 20, 50, and 80 degrees C. Type II equilibrium and bimodal kinetic behavior that was governed by a rapid initial uptake followed by a prolonged sorption over a larger time scale was observed. In order to explain this bimodal behavior, the major components of this foam-the silicone polymer and the diatomaceous earth-were independently studied for their water equilibrium behavior and uptake kinetic characteristics. Type II equilibrium was observed for both components. The kinetic behavior of the silicone polymer was governed by a very rapid uptake of water. The kinetic behavior of the diatomaceous earth was governed by a rapid initial uptake followed by a prolonged sorption over a larger time scale. A physically based and thermodynamically consistent mathematical model describing the water equilibrium and kinetics in diatomaceous earth and silicone polymer components, was employed to characterize the data. This model formed the basis of a predictive model for estimation of water sorption in filled silicone foam. The predictive model was tested against sorption and desorption data yielding favorable results for a range of temperatures.
Introduction to Minerals
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Applied Mineralogy: Applications in Industry and Environment
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Industrial minerals and their uses, Library of Congress Catalog
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Study of chemical and physical properties of perlite and its application in India
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Properties and Applications of Zeolites, American Journal of Materials Science, 7(5), 196-221 (2017).