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1.
Six different Ca‐zeolite minerals are widespread in various assemblages in late fissures and fractures in granites and gneisses of the Swiss Alps. The zeolites formed as a result of water–rock interaction at relatively low temperatures (<250 °C) in the continental upper crust. The zeolites typically overgrow earlier minerals of the fissure assemblages, but zeolites also occur as monomineralic fissure fillings. They represent the youngest fissure minerals formed during uplift and exhumation of the Alpine orogen. A systematic study of zeolite samples showed that the majority of finds originate from three regions particularity rich in zeolite‐bearing fissures: (i) in the central and eastern part of the Aar‐ and Gotthard Massifs; (2) Gibelsbach/Fiesch, in a fissure breccia located at the boundary of Aar Massif and Permian sedimentary rocks; and (3) in Penninic gneisses of the Simano nappe at Arvigo (Val Calanca). Rail and road tunnel construction across the Aar‐ and Gotthard Massif provided excellent data on zeolite frequency in Alpine fissures. It was found that 32% (Gotthard NEAT rail base tunnel, Amsteg section) and 18% (Gotthard road tunnel) of all studied fissures are filled with zeolites. The number of different zeolites is limited to six species: laumontite, stilbite and scolecite are abundant and common, whereas heulandite, chabazite and epistilbite occur occasionally. Calcium is the dominant extra‐framework cation, with minor K and Na. Heulandite and chabazite contain Sr up to 29 and 10 mol.% extra‐framework cations respectively. Na and K contents in zeolites tend to increase during growth as a result of changes in fluid composition and/or temperature. The K enrichment of stilbite found in surface outcrops compared to subsurface samples may indicate late stage cation exchange with surface water. Texture data, relative age sequences derived from fissure assemblages and equilibrium calculations show that the Ca‐dominated zeolites precipitated from fluid with decreasing temperature in the order (old to young = hot to cold): scolecite, laumontite, heulandite, chabazite and stilbite. The necessary components for zeolite formation are derived from dissolving primary granite and gneiss minerals. The nature of these minerals depends, among other factors, on the metamorphic history of the host rock. Zeolites in the Aar Massif derived from the dissolution of epidote, secondary calcite and albite that were originally formed during Alpine greenschist metamorphism from primary granite and gneiss assemblages. Zeolite fissures occur in areas of H2O‐dominated fluids. This is consistent with equilibrium calculations that predict a low CO2 tolerance of zeolite assemblages, particularly at low temperature. 相似文献
2.
The paper deals with results of general and systematic analysis of data from deep-sea drilling (360 stations) and a personal study carried out by the authors on the distribution and facies location of authigenic zeolites in the sedimentary mantle of the World Ocean.The scheme of zeolite distribution, compiled for the Holocene—Pleistocene, Miocene, Eocene and Cretaceous periods confirmed the previously established global stratification of zeolites. It showed that the main mass of phillipsite was formed during the Pleistocene—Holocene, while clinoptilolite was a predominant mineral in Eocene and Cretaceous rocks. Both zeolites were wide-spread in the Oligocene and Miocene. Facies location and paragenesis of associated minerals as well as the original material of their formation are different for phillipsite and clinoptilolite.The most probable reasons for vertical stratification of oceanic zeolites of global significance are changes of the character of volcanism in time and general evolution of sedimentation in the World Ocean. 相似文献
3.
《International Geology Review》2012,54(1):15-44
Zeolites are among the most common products of chemical interaction between groundwaters and the Earth's crust during diagenesis and low-grade metamorphism. The unique crystal structures of zeolites result in large molar volumes, high cation-exchange capacities, and reversible dehydration. These properties influence both the stability and chemistry of zeolites in geologic systems, leading to complex parageneses and compositional relationships that provide sensitive indicators of physicochemical conditions in the crust. Observations of zeolite occurrence in Tertiary basaltic lavas in the North Atlantic region indicate that individual zeolite minerals are distributed in distinct, depth-controlled zones that parallel the paleosurface of the plateau basalts and transgress the lava stratigraphy. The zeolite zones are interpreted to have formed at the end of burial metamorphism of the lavas. Relative timing relations between various mineral parageneses and crustal-scale deformal features indicate that the minerals indicative of the zeolite zones formed within 1 million years after cessation of volcanism. Empirical correlation between the depth distribution of zeolite zones and the temperatures of formation of zeolites in geothermal systems provides estimates of regional thermal gradients and heat flow in flood-basalt provinces. Similarly, the orientations of zeolite zones can be used to distinguish synvolcanic and post-volcanic crustal deformation. Because zeolites that characterize the individual zones display different ion-exchange selectivities for various cations, reactions between groundwaters and zeolites in basaltic aquifers can result in depth-controlled zones where individual elements are concentrated in the crust. This is established for Sr, which is concentrated by at least an order of magnitude in heulandite, resulting in an overall Sr enrichment of lavas in the heulandite-stilbite zeolite zone. 相似文献
4.
Experimente zur Zeolithbildung durch hydrothermale Umwandlung 总被引：1，自引：0，他引：1
Helmut Höller Ulrike Wirsching Mahmud Fakhuri 《Contributions to Mineralogy and Petrology》1974,46(1):49-60
The formation of zeolites by hydrothermal alteration has been investigated by taking trass from the Laach volcanic area as a sample. Zeolites to be found are chabazite, phillipsite and analcime, all of which originated from the same phonolitic glass. This paper aims at explaining the formation of zeolites by means of experimental alteration of the pumice with various solutions. NaOH and KOH solutions were used in the experiments, these limited the formation conditions of chabazite, phillipsite, analcime in alkaline environments. Moreover, experiments were carried out with H2O dist and with solutions that formed during the alteration of pumice by reacting with H2O. These experiments were conducted to supply clues concerning the formation of zeolites in the Laach volcanic area. With NaOH solutions zeolites were formed from pumice within a temperature range of 70 to 250° C and a concentration range of 0.001 to 1.0 n; with KOH solutions they were formed in the same concentration range within a temperature range of 100 to 250° C. The formation of zeolites proved to depend much on temperature and concentration: At low temperatures high concentrations are necessary, higher temperatures need lower concentrations. With NaOH solutions the zeolites are formed in the succession, chabazite, phillipsite, analcime at increasing temperatures and increasing concentrations. With KOH solutions the same succession is to be found with rising temperature. With rising concentration, however, this succession is changed at higher temperatures: Phillipsite appears in place of analcime at high temperatures and concentrations. By the alteration of pumice with H2O, zeolites are formed from 200° C onward. With solutions that had been formed during the alteration of pumice by reacting with H2O, the minimum temperature for the formation of zeolites was 180° C. Concerning the genesis of zeolites in the Laach volcanic area, the experiments showed that the temperature for the formation of analcime was about 250° C; for the formation of chabazite and phillipsite it was between 150 and 190° C. The pH of the reacting solutions may have been between 7 and 8. Thus the experiments proved that from the same material different zeolites, chabazite, phillipsite, analcime may be formed by temperature change of the reacting solutions (H2O to slightly alkaline solutions). 相似文献
5.
Ismael S. Ismael Ahmed Melegy Tomas Kratochvíl 《Geotechnical and Geological Engineering》2012,30(1):253-262
Hazardous metal cations enter water through the natural geochemical route or from the industrial wastes. Their separation
and removal can be achieved by adsorptive accumulation of the cations on a suitable adsorbent. In the present work, toxic
Pb(II) ions are removed from water by accumulating it on the surface of natural zeolite in three different forms; one untreated
and two treated samples, one sample treated with 2 M HCI solution and other is treated with 3 M NaOH solution. Natural zeolite
is mainly composed of clinoptilolite, and mordenite, with amount of non-zeolite phase (smectite and illite) and C and CT opal.
The adsorption experiments are carried out using a batch process in environments of different pH, initial Pb(II) concentration,
interaction time and amount of zeolites. Treated zeolite samples show high exchange capacity for Pb(II) compared to untreated
sample, however, acid-treated sample shows an exceedingly good exchange capacity. Equilibrium data fitted well with the Langmuir
isotherm model with maximum adsorption capacity of 115, 126, and 132 mg g−1 of untreated natural zeolites, alkali-treated zeolites and acid-treated zeolites respectively. The rates of adsorption were
found to confirm to pseudo-first order kinetic with good correlation and the overall rate of lead ions uptake. 相似文献
6.
Ulrike Wirsching 《Contributions to Mineralogy and Petrology》1975,49(2):117-124
In the formation of zeolites by hydrothermal alteration volcanic glasses are the starting material in most cases. The experiments aimed at demonstrating in what way the chemistry of the volcanic glass influences:
- the alteration rate of the volcanic glass to zeolites,
- the kind of zeolites being formed and their formation conditions.
7.
13X沸石分子筛的比表面积和孔分布 总被引：2，自引：0，他引：2
对利用钾长石粉水热合成的13X沸石分子筛分别进行了比表面积和孔分布测定。结果表明:13X沸石分子筛比表面积约为621.50~747.40 m2/g,总孔体积约为0.344 70~0.393 70 cm3/g;具有高比例且孔径小于2.50 nm的微孔,中-小型实验样品(SXZ-10g和SXZ-1kg)的微孔体积比例相近,为81.33%~84.70%,而扩大实验样品(SXZ-10kg)的微孔体积比例为67.90%~67.98%。13X沸石分子筛微孔的含量是决定13X沸石分子筛具有高比表面积和高效吸附性能的前提。 相似文献
8.
天然沸石吸附性能与阳离子组分之间的关系 总被引：7，自引：0，他引：7
吸附性能是沸石矿物的重要特性之一，也是相关领域应用的重要依据。以嫩江、海林和穆棱三大沸石矿床为例，通过对天然沸石矿的化学成分、沸石类型、矿石品位（CEC值）、比表面积及吸附性能的系统研究与对比分析，总结天然沸石矿附吸性能差异变化规律与原因。研究表明，天然沸石对气体CO2、H2S、SO2、NO2和气态H2O的吸附容量均与其（CaO MgO)/(Na2O K2O)比值之间呈正相关性关系，富二价阳离子组分者吸附容量大，富一价阳离子组分者吸附容量较小。据此，可作为天然沸石矿吸附性能预测评价的重要依据。 相似文献
9.
活化沸石除铵及其动力学过程研究 总被引：1，自引：1，他引：1
对新型水处理材料活化沸石去除水中氨氮的各项性能进行了研究。单因素影响试验表明,沸石用量、粒径、溶液温度、浓度、pH值及吸附时间对去除效果有重要影响。据此确定了最佳静态试验条件,在该条件下,活化沸石对水中的氨氮有较好的去除效果,可将生活污水中的120 mg/L氨氮降到40 mg/L。动态小试确定了小试设备的工艺参数,该处理设备在实际运行过程中,吸附周期为64 h,处理效果良好。动力学研究表明,活化沸石除铵是离子交换与吸附两种行为共同作用的结果,该过程符合Freundlich等温式,动力学方程可用一级反应来描述。 相似文献
10.
沸石类胶结物是准噶尔盆地西北缘玛南地区二叠系乌尔禾组发育的一种特殊胶结物类型。通过岩心观察、薄片鉴定、扫描电镜分析与岩石组分统计,明确了玛南地区乌尔禾组沸石胶结物的矿物特征、空间分布、成因机理与成储机制。研究区乌尔禾组主要发育浊沸石与片沸石,其中片沸石分为两期,早期富铁,晚期贫铁。研究区沸石胶结物的空间分布规律并不明显,仅在垂向上,从乌尔禾组到百口泉组,浊沸石与片沸石含量具有逐渐降低的趋势。沸石类胶结物的形成主要受控于母岩中凝灰岩砾石组分,中酸性火山岩砾石不利于浊沸石的形成,其他火山岩砾石与沸石的形成无明显关系,浊沸石大量发育的次生溶蚀孔隙是研究区油气赋存的主要储集空间类型。沸石类胶结物的沉淀与溶蚀可以简化为两阶段成岩作用过程,早期正常成岩胶结形成各类沸石胶结物,晚期深部成岩流体上涌,对储层进行溶蚀与改造,深部流体改造是成储的关键阶段。 相似文献
11.
12.
Deyi Wu Bohua Zhang Li Yan Hainan Kong Xinze Wang 《International Journal of Mineral Processing》2006,80(2-4):266-272
Hydrothermal conversion of fly ash into zeolites was conducted and the effects of the addition of sodium halide and waste solutions produced after zeolitization of fly ash, as well as the adjustment of the Si/Al ratio prior to synthesis process on the formation and cation exchange capacity (CEC) of zeolite product were evaluated. Both the addition of NaCl and NaF ameliorated the crystallinity and CEC of synthesized zeolite, but NaF had a better improvement effect. Na+ was considered to enhance the crystallization of zeolite, while F− favored the dissolution of fly ash. The type of zeolite formed depended on the Si/Al ratio of the starting material prior to the nucleation and crystallization of zeolite. The adjustment of the Si/Al ratio of fly ash by addition of Na2SiO4 and Al(OH)3 changed the type and CEC of zeolite. Waste solutions contained large amount of Si and little Al due to the formation of a zeolite named NaP1 in zeolite terminology with the Joint Committee of Powder Diffraction Standard (JCPDS) code of 39-0219. The alkalinity decreased largely. As a result, the CEC value of zeolite products synthesized with waste solution as alkali source decreased. The supplementation of new alkali to adjust the alkalinity of waste solution could enhance the CEC of synthesized product. It was concluded that: (1) addition of sodium halide and adjustment of the Si/Al ratio prior to synthesis can improve the quality of zeolite; (2) waste solutions produced following the zeolitization of fly ash can be reused as an alkali source in the activation of fly ash; zero-emission of waste solution in the synthesis of zeolite from fly ash is possible. 相似文献
13.
《Applied Geochemistry》2006,21(6):993-1005
The direct synthesis of zeolites in polluted soils has proved to be a promising process for the stabilization of metals inside these minerals. Nevertheless, more detailed information about this process is still needed in order to better foresee the fate of metals in treated soils. In this work, zeolite X has been synthesized under alkaline conditions in an aqueous solution containing 2500 mg kg−1 of Cu, starting from Na silicate and Al hydroxide at 60 °C. Aluminium, Si and Cu concentrations in the aqueous phase, during zeolite synthesis, were measured over a period of 160 h. The solid products have been characterized over time by XRD, SEM-EDX, ESR, FT-IR, and synchrotron radiation X-ray microbeam absorption near edge structure (μ-XANES) and extended X-ray absorption fine structure (μ-EXAFS) spectroscopy. It appears that the marked reduction of Cu concentration in solution is not only due to a simple precipitation effect, but also to processes connected with the formation of zeolite X which could entrap, inside its porous structure, nano- or micro-occlusions of precipitated Cu hydroxides and/or oxides. In addition, EXAFS observations strengthen the hypothesis of the presence of different Cu phases even at a short-range molecular level and suggest that some of these occlusions could be even bound to the zeolite framework. The results suggest that zeolite formation could be used to reduce the availability of metals in polluted soils. 相似文献
14.
《矿物学报》2013,(Z1)
Ca-bentonite can be converted into zeolites A through hydrothermal alkaline treatment by varying the synthetic parameters. This study focuses on the effect of initial Si/Al molar ratio, NaOH concentration on the type of formed zeolite A. The Ca-bentonite (China, Fuxin)were mixed with an aqueous NaOH solution, Al(OH)3 powder and hydrothermally treated at about 90 ℃,12 h. Different types of zeolites (zeolite X, P, and A),sodalite were synthesized after the treatment. Zeolites were characterized and quantified by means of XRD and SEM analysis. Zeolite A predominantly formed with 0.5≤Si/Al≤2.0 was produced and zeolite X, P formed with Si/Al>2.0 under the 2.2mol/LNaOH concentration; Sodalite was also formed under high NaOH molarities. Shape of zeolite A is show the cube by the SEM micrograph. 相似文献
15.
A. E. Khardikov 《Lithology and Mineral Resources》2001,36(2):134-140
Paleocene and Eocene terrigenous–siliceous complexes of the Eastern Ciscaucasus contain 18–92% zeolites represented by clinoptilolite. The studied complexes are the stratified subplatformal shallow-water subaqueous deposits with abundant authigenic silica as skeletal remains, cryptocrystalline substance, and pyroclastic material. Clinoptilolite in Paleocene–Eocene terrigenous–siliceous sediments formed from the mud solutions mainly at the expense of the labile pyroclastic material and biogenic silica. Variations in the zeolite abundance are explained by different contents of the pyroclastic material and SiO2in the primary sediment. 相似文献
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18.
Maria L. Fercia Roberto Lonis Roberto Peretti Antonio Sau Antonello Serci Antonio Zucca 《Resource Geology》2009,59(1):15-24
An investigation was conducted into the Tertiary ignimbrite formations in the Romana area in NW Sardinia. Scanning electron microscopy–energy-dispersive spectrometry indicated the presence of clinoptilolite and subordinate smectite, quartz, mordenite and calcite. Laboratory analyses of representative samples collected from the deposit indicated a cation exchange capacity ranging from 85 to 135 mEq per 100 g. Ion exchange experiments conducted in flasks containing different initial cation concentrations and in columns supplied with solution having constant cation concentration, showed different selectivity towards the cations examined, in the order: NH4 + > Pb2+ > Cd2+ > Cu2+ > Zn2+ > Mn2+ > Ni2+ . Compared to the untreated material, under the experimental conditions used and considering the eluate, and the Italian regulatory limits for discharge into surface waters, the zeolite treated with a 1-N NaCl solution yielded a 1.3–5-fold increase in the volume of treated water, depending on the cation examined. The experimental results obtained show that the cationic exchange properties of the zeolite rock from the Romana deposit are comparable with the average quality of zeolites currently imported into Italy from non-European countries. 相似文献
19.
Part I: Chemical and structural effects of cation-exchange
Attempts were made to prepare, by appropriate exchange methods, homoionic samples of phillipsite, gismondite, harmotome, chabazite
and gmelinite containing Ba, Ca, K, Na or Li-ions. Powdered natural samples were used as starting material. All samples were
analysed chemically before and after the cation exchange. The results of the analyses demonstrated clearly that the „exchange
capacity“ depends on the method used, the structure of the zeolite and the nature of the cation involved in the exchange.
The analyses also disclosed the important fact that the ratio in Mole % of the sum of exchangeable cations: Al2O3 of the natural and of the exchanged samples is generally <1, and can be as low as 0.74. Examples are presented where cation
exchange results in a substantial change in the framework structure.
Part II: Dehydration behavior and structural changes at elevated temperatures
Samples of the natural zeolites mentioned above, and of some of their cation exchange products were dehydrated in air of controlled
humidity up to 600° C. The slopes of the weight loss curves of chabazite and gmelinite are continuous, whereas those of phillipsite,
gismondite, and harmotome show a discontinuity between 90–190° C, indicating the existence of two discrete hydrated phases
for each of these zeolites. High temperature x-ray studies of powdered samples confirmed this result. The high temperature
hydrates of phillipsite, gismondite, and harmotome persist reversibly up to approximately 230° C. At higher temperatures,
new probably anhydrous phases form. Gmelinite, at 240° C, transforms irreversibly to anhydrous gmelinite which is stable up
to >700° C. The transition was studied by single crystal techniques. The chabazite structure remains intact up to >700° C.
The absolute water content and the dehydration behavoir of the zeolites investigated are primarily dependent on the nature
of the exchange cation. The structural changes at elevated temperatures are determined by the silica alumina framework.
Part III: Hydrothermal stability* and interconversions
The stability of phillipsite, gismondite, harmotome, chabazite, gmelinite, their exchange products, and of the synthetic Linde
zeolites Faujasite and Type A was studied in the temperature range between 150° and 350° C at a constant pressure of 1000
atm of H2O. Between 180° and 260° C all examined Sodium and Calcium zeolites were metastable with respect to analcite (wairakite**).
Phillipsite and sodium-rich zeolites generally converted to analcite (wairakite) directly. Caex-chabazite and Caex-gmelinite formed phillipsite, whereas Ca-gismondite and Ca-Type A formed natrolite as intermediate phases. Li-gmelinite converted
to bikitaite***. (This represents the first successful preparation of natrolite and bikitaite. Attempts starting from gels
or glasses have been unsuccessful so far.) Ba-gmelinite converted to harmotome at 250° C. This transformation was studied
microscopically and by single crystal x-ray techniques.
The transformations that take place on hydrothermal treatment as well as on low temperature cation exchange of zeolites (see
Part I) indicate that, unlike the conditions prevailing in clays, the type of cation and the ratio of cations in the exchange
positions have an important influence on the structure of the silicaalumina-oxygen framework. This explains two phenomena:
The lack of solid solution between two potential end members of a solid solution series (for instance phillipsite-gismondite),
and the large number of different zeolites in nature, where a great variety in the ratios of available alkali and alkaline
earths ions must be expected.
Any classification of zeolites becomes still more difficult in view of the fact that conversions among different groups (chabazite
→ phillipsite) and different structures (three-dimensional framework → fibre) take place relatively easily.
Contribution No. 59–92, College of Mineral Industries, The Pennsylvania State University, University Park, Pennsylvania. 相似文献
20.
The kinetics and mechanism of hydrothermal formation of zeolite A from natural kaolinites have been studied using as starting
materials two international kaolinite standards (KGa-1 and KGa-2 from Georgia, USA) exhibiting a different degree of stacking
disorder. Precursors utilized for the synthesis were prepared by heating the kaolinites at 800 °C. Metakaolinite was also
prepared from KGa-1 by thermal activation at 600 °C. The hydrothermal syntheses were accomplished by heating the samples in
NaOH solutions at temperatures between 70 and 110 °C. The kinetic experiments were performed by time-resolved synchrotron
powder diffraction in isothermal mode using a transmission geometry and an Image Plate detector. The results of the kinetic
analysis are interpreted in the light of the structural state of the starting kaolinite, and of the temperature of activation
of the precursor material. For kaolinite activated at high temperature the nucleation and crystallization of zeolite A is
essentially independent of the defect density of the original kaolinite, and the thermal history of the precursor seems to
be the main controlling parameter. The formation process of zeolite A from metakaolinite materials obtained at lower activation
temperatures shows significantly faster reaction rates and lower apparent activation energies. This is again interpreted in
the light of the short range inhomogeneities present in metakaolinite. As the reaction proceeds metastable zeolite A transforms
into hydroxy-sodalite.
Received April 18, 1996 / Revised, accepted September 27, 1996 相似文献