共查询到20条相似文献，搜索用时 265 毫秒
1.
2.
在地球科学实验中,氧逸度、氢逸度是反映待测体系的氧化还原状态和制约体系发展过程的重要参数。本文阐述了钇稳定氧化锆（YSZ）的导电机理和不同稳定剂（Y2O3）掺杂量对性质的影响,并列举了实验地球化学中利用YSZ传感器测定体系氧逸度、氢逸度及pH值的方法。与已有的其他氧/氢逸度测量方法相比较,YSZ传感器在实验中有耐高温、高压、抗腐蚀性强、响应快、原位测定特性好等诸多优点。最后指出了YSZ在应用于实验过程中的存在问题。随着陶瓷制作技术、微机械加工技术和微电子技术的发展,YSZ在地学实验中的应用将更加多样化和具有针对性。 相似文献
3.
至今 ,自然尚未找到立方氧化锆矿石或矿床 ,它是天然氧化锆 (单斜相 )在一定条件下产生相变 ,经四方相、六方相而转变为具原子最紧密堆积的立方相的。随着相变的产生 ,其性能也发生转变 ,立方相氧化锆具有折射率高 (2 1 5-2 2 3 )、色散大 (0 0 6)、硬度较高 (摩氏 8 0 -8 5 )、化学稳定性好等特性。因为钻石的折射率为 2 42 ,色散为 0 0 44 ,所以若把二者琢磨成相同的戒面 ,其综合效果非常相似。因此 ,立方氧化锆成了钻石最佳的代用品 ,目前 ,用冷坩埚熔壳法已成功地生产出立方氧化锆。立方氧化锆的相变温度为 2 3 70 -2 75 0℃ ,要使… 相似文献
4.
钻石与合成立方氧化锆外观相似，在没有鉴定仪器的条件下，使用10倍放大镜和肉眼观察颜色、光泽、色散、瑕疵、加工工艺、腰围等，辅以透字试验、亲油性实验、称重、测量直径等简单方法即可将钻石与合成立方氧化锆快速鉴别。 相似文献
5.
高温高压下水流体的pH值是影响矿物-水流体相互作用平衡和动力学过程的一个重要参数。确定高温高压流体pH的方法主要包括电位势测量、化学分析与热力学计算及电导率方法。电位势测量在化学领域应用广泛,也被用来测量了洋中脊的热液流体的pH值。人们尝试了各种形式的电极,如氢电极、钯氢化物电极、金属-金属氧化物电极和钇稳定的氧化锆(YSZ)电极。玻璃电极只取得了有限的成果,通常用来测量常温及低温下的流体的pH值。对金属-金属氧化物电极在较宽的温度范围内进行了研究,但它需要利用合适的参比溶液来校正,与玻璃电极一样都表现出较大的偏移和误差以及不可回测性。陶瓷薄膜电极,如钇稳定的氧化锆(YSZ)电极,为测量相对较高温度下的pH值提供了一个可靠的方法。利用高温淬火水的化学分析和常温下的pH的测量,通过求解络合反应质量平衡与所有组分质量平衡的联立方程,来计算指定温度压力下pH值和水溶液种类的分布,是获得高温pH值的另一个重要而常用的方法,但热力学数据中的数值误差和不确定性以及分析误差能够影响计算出的高温溶液的pH值的精度。对高温高压超临界水流体的电导测量已经取得很大的成就,它被用来作为确定溶液内部离子反应平衡常数的一种最常用的方法,通过获得的这些反应的平衡常数,就可以得到在高温高压下流体的就位物质组成,这个方法可以测量更高温度压力下流体的pH值。 相似文献
6.
针对深井钻进中，钻头受高温环境影响，钻头胎体性能显著下降的技术难题，研究了空心球种类、空心球目数、空心球添加量等对热压烧结金刚石钻头胎体常温及高温力学性能的影响。结果表明：在胎体基体内添加空心球，宜添加3540目数的钇稳定的氧化锆空心球；当钇稳定的氧化锆空心球的添加量为10%时，胎体的综合性能达到最佳，冲击韧性和抗弯强度也达到最大值，分别为3 J/cm2和903.75 MPa。添加适量空心球的胎体复合材料，由于球形孔隙结构的存在，使得胎体表面粗糙度得到增强，提高了金刚石钻头的胎体出刃性能、高温下的力学性能。 相似文献
7.
氢乃是自然界中最小、最轻、迁移最快、反应能最强的气相元素。笔者(1989)曾经提出,氢主要储存于外地核液态铁之中[1],其在巨大的压力梯度、温度梯度、质量梯度及黏度梯度中自发向上、强力喷射,构成了最伟大的地球内动因。本文系统探讨了氢的种种地球化学特性,特别是氢流对地球深部物质成分氢化迁移的特殊功能。 相似文献
8.
烃类的有机(生物)与无机(非生物)来源--油气成因理论思考之二 总被引：6，自引：1，他引：5
自然界烃类的大规模形成是有机-无机物质相互作用的结果。在烃类物质两大组成元素中,碳的来源多以有机质为主,特别是液态烃,而氢却有多种来源。有机氢来自有机质,无机氢主要来自同沉积水,还有深部挥发分中的氢,同沉积水中的氢则以多种途径进入烃类。本从油田水的垂向演化及其与非油田水的对比、烃类物质的氢同位素组成及其与源岩沉积环境的关系、成烃加水与否的模拟实验,以及世界大型油气田分布与构造带的关系等方面,论述了烃类形成的有机与无机的相互作用,特别是烃类中氢的无机来源的本质,并对氢的来源及其加氢作用机制进行了分析,对油气形成理论的完善和在油气勘探中的应用有一定参考价值。 相似文献
9.
产氢菌的发现是近代微生物学研究的一大重要进展。地质体中的氢代谢（氢的生成和利用）是微生物降解有机质形成烃类的重要环节。在石油生成过程中,氢是重要的中间产物及主产物。大分子化合物分解为小分子化合物、脱去含氧基团、烯烃成为饱和烃均需要补充氢。没有氢代谢便没有石油的大量生成。产氢菌含有氢化酶,具有生成H2的能力。一部分微生物在降解有机质的过程中形成H2,另一部分微生物利用H2进行生命活动,产氢耗氢一直处于一种稳定的动态平衡,产氢微生物只有在耗氢微生物存在下才能生长。耗氢微生物的耗氢作用又促进了产氢反应的连续进行,这种微生物的互营联合,发生在石油形成过程中的各个阶段。氢转移是厌氧降解有机质区别于有氧降解有机质的最重要特征。微生物生长繁殖受温度、营养及沉积环境的影响,从浅层至深层,微生物种群不断更替,原有的种群因环境改变而死亡,新的种群又会大量繁殖,死亡的微生物输入至沉积层便成为烃类。酶是一种具有催化活性的蛋白质,微生物的一切生命活动都离不开酶。一种酶只能催化一种反应或一类反应的完成,各阶段都有独特的酶系统,酶在完成专属代谢途径后,可转化成石油组分,如叶绿素转化成甲烷菌F430辅酶,再转化成卟啉。地层温度促进了有机质热裂解,使有机质中的C-C键断裂发生得更加频繁;厌氧微生物的降解作用也使有机质发生降解。二者方向相同,互为融合,使有机质的裂解加速。微生物对有机质改造形成烃类,其中脱去含氧官能团、产氢用氢形成饱和烃等作用,对讨论石油和天然气的形成具有重要意义。 相似文献
10.
11.
《International Geology Review》2012,54(6):621-625
Rock distribution (climate indicators) and plant composition indicate a broad belt of arid and semiarid climate in the subtropics of the Northern hemisphere at the beginning of the Late Jurassic. Coal-bearing or gray terrigenous formations were replaced by redbeds and frequently carbonate sequences with deposits of gypsum and sometimes rock salt. The moisture-loving forest vegetation, in which gingkos, podozamiticLs, some conifers (upper level), fems, cycads, and bennettitids (lower level) predominated, was replaced under the influence of desiccation by a sparse vegetation, consisting mainly of cheirolepids (a group of extinct Mesozoic conifers) and bennettitids, probably represented by low-growing woody forms. In the belt of moderately warm moist climate developed to the north, a moisture-loving conifer-ginkgo forest grew and coal continued to form. —Authors. 相似文献
12.
B. N. Ryzhenko N. I. Kovalenko N. I. Prisyagina N. P. Starshinova V. V. Krupskaya 《Geochemistry International》2008,46(4):328-339
The solubility of ZrO2(baddeleyite) in HCl, HF, H2SO4, NaOH, and Na2CO3 solutions was determined by the capsule method at 500°C and 1000 bar. Baddeleyite is the only solid phase detected in the experimental products. Based on the ZrO2(baddeleyite) solubility measurements, the values of equilibrium constants at 500°C and 1000 bar (consistent with the Gibbs free energies of all the reactants) were obtained for the following reactions: ZrO2(cr) + H2SO 4 0 = Zr(OH)2OH 4 0 (pKo = 4.95), ZrO2(cr) + 2H2SO 4 0 = Zr(SO4) 2 0 ) + 2H2O (pKo = 3.74), ZrO2(cr) + H2O + HF0 = Zr(OH)3F0 (pKo = 3.35), ZrO2(cr) + 2HF0 = Zr(OH)2F 2 0 (pKo = 2.37), and ZrO2(cr) + 2H2O + OH? = Zr(OH) 5 ? (pKo = 4.39). Ionization constants were estimated for the chloride, fluoride, sulfate, and hydroxo complexes of zirconium. Using the experimental data and thermodynamic information derived from experiments and the electrostatic model of the ionization of electrolytes, it was shown that no more than n mg zirconium per one kilogram H2O can be accumulated in high-temperature fluids at 500°C and 1000 bar. 相似文献
13.
Maria Schönbächler Mark Rehkämper Manuela A. Fehr Alex N. Halliday Bodo Hattendorf 《Geochimica et cosmochimica acta》2005,69(21):5113-5122
Stepwise dissolutions of the carbonaceous chondrites Orgueil (CI), Murchison (CM) and Allende (CV) reveal large nucleosynthetic anomalies for Zr isotopes that contrast with the uniform compositions found in bulk meteorites. Two complementary nucleosynthetic components are observed: one enriched and one depleted in s-process nuclides. The latter component, characterized by excess 96Zr, is most distinctive in the acetic acid leachate (up to ε96Zr ≈ 50). The excess decreases with increasing acid strength and the final leaching steps of the experiment are depleted in 96Zr and thus enriched in s-process nuclides. Presolar silicon carbide grains are likely host phases for part of the anomalous Zr released during these later stages. However, by mass balance they cannot account for the 96Zr excesses observed in the early leaching steps and this therefore hints at the presence of at least one additional carrier phase with significant amounts of anomalous Zr. The data provide evidence that average solar system material consists of a homogenized mixture of different nucleosynthetic components, which can be partly resolved by leaching experiments of carbonaceous chondrites. 相似文献
14.
L. N. Kogarko 《Doklady Earth Sciences》2016,468(2):598-601
For the first time, fractionation of zirconium and hafnium in carbonatized mantle xenoliths from the eastern Antarctic has been studied. An elevation relative to the chondrite values of Zr/Hf in the metasomatized xenoliths has been revealed. The main reactions of the carbonate metasomatism lead to replacement of primary orthopyroxene by secondary clinopyroxene. A substantial broadening of the clinopyroxene crystallization field results in an increase of Zr/Hf in an equilibrated melt due to a higher partition coefficient of Hf in clinopyroxene, relative to that of Zr. Migration of reaction-active carbonate and carbonate–silicate melts, equilibrated to metasomatic wehrlite, causes an increase in the Zr/Hf value in the carbonatized mantle substrate. 相似文献
15.
《International Journal of Mineral Processing》2005,76(4):234-243
Zircon is the most important commercial source of zirconium, its compounds and alloys. Several methods are used for industrial processing of zircon for production of zirconium dioxide and tetrachloride. These methods include sintering of zircon with sodium carbonate or sodium hydroxide or calcium oxide or calcium carbonate and with potassium fluorosilicate, chlorination of zircon mixture with coal in blast furnace and carbidization of zircon in a mixture of coal in electric arc furnace. All these methods are carried out at high temperatures and have many disadvantages.The present work illustrates a study of a new technique for extracting zirconium from Egyptian zircon concentrate by its simultaneous ball-milling and pressure alkaline leaching, to improve the recovery of zirconium from zircon. Experiments were carried out in stainless steel ball-mills of cylindrical shape under different conditions of temperature, pressure and time. The ball-mills were heated and mechanically rotated in an electric furnace by means of roll mechanism.The filtrate after leaching of zircon, containing excess of sodium hydroxide was regenerated by its treatment with calcium hydroxide for purification from silicon impurity. Then, the solution was evaporated to the desired concentration (500 g/l Na2O) and recycled to the reactor of leaching.The results obtained show that complete recovery of zirconium from zircon (99.7%) by simultaneous ball-milling and alkaline leaching was attained at 250 °C within 3 h, using amount of sodium hydroxide 150% of theoretical requirement (satisfying favourable conditions of zirconate cake for subsequent acid leaching).The standard free energy (ΔFo) and equilibrium constant (K) of the reaction of zircon with sodium hydroxide were calculated as—19.58 k cal mol− 1 and 2.29 · 1014, respectively. The kinetics of the technological alkaline processing of zircon in ball-mall autoclaves was studied over the temperature range 150–275 °C. 相似文献
16.
《International Geology Review》2012,54(12):1795-1797
At 500–600°C and 500–800 atm, in alkaline solutions, two mechanisms of the migrations of Ti, Zr, and Hf are experimentally indicated: a) in the absence of fluorine and other halogens, these metals migrate as titanates, zirconates, and hafnates of K and Na, the forms which are conducive to their dissipation but not deposition-accumulation in the rocks, within a wide range of temperature, as long as the pH of the solution remains alkaline; b) in the presence of fluorine, Ti, Zr, and Hf migrate as fluoride complexes (with Na and K) from which they may be liberated by hydrolysis and deposited at decreasing temperature, as the corresponding oxides. 相似文献
17.
非洲的锆资源丰富,沿海岸带成群连片分布。通过对非洲51个锆矿床（点）的地质特征、时空分布及勘查开发历史和现状等进行分析研究,查明非洲的锆资源具有分布集中、规模大、易采易选,伴生矿物种类多,综合利用价值高等特点。非洲已查明锆储量占全球52%,其中莫桑比克、南非、马达加斯加、塞内加尔和肯尼亚集中了非洲99%的锆矿资源。矿床类型以滨海锆砂矿为主,矿体多为平行海岸线的沙丘群,通常为上新世-全新世未固结的薄而平坦的砂层,走向延伸10~100km,重矿物以锆石、金红石和钛铁矿为主,含量2%~12%。非洲锆矿的勘查始于20世纪20年代的尼罗河三角洲,开发始于20世纪50年代的南非,特诺、力拓等大型矿业公司是非洲锆矿开发的主力,济南域潇集团等中资企业近年来积极参与。非洲的锆矿开发主要集中在南非和莫桑比克,近10年来的产量约占全球锆产量的40%,成为全球主要锆资源供应地。马达加斯加和肯尼亚的锆矿资源丰富,是与中国签署共建“一带一路”谅解备忘录的国家,与中国在锆矿资源领域的合作潜力巨大。 相似文献
18.
Masako Shima 《Geochimica et cosmochimica acta》1979,43(3):353-362
The concentrations of Ti, Zr and Hf have been determined, by a stable isotope dilution method, in 27 chondrites, seven achondrites and standard rock samples BCR-1 and W-1.Among all chondrites investigated, enstatite chondrite Abee is lowest in Ti atomic ratio compared with Si while all carbonaceous chondrites show higher values. The Zr contents are higher in CII and CIII chondrites, relative to the other groups of chondrites. There is a clustering of Ti and Zr within each group. The ratios in CII, CIII. E and H chondrites are essentially the same, while that in the CI chondrite is lower and in L, LL and unequilibrated chondrites are higher.The concentrations of Ti, Zr, Hf and , ratios in achondrites are variable, even among members of the same group.Based on these results, condensation models for these elements are discussed. The variable results for Ti, Zr and Hf in achondrites may be due to the reheating recrystallization and metamorphic processes.‘Cosmic atomic abundances’ of Ti, Zr and Hf are calculated as 2470, 11.2 and 0.185. respectively for Si = 106 atoms. 相似文献
19.
Miloš René 《地学学报》2008,20(1):52-58
The mobility of REE, Y and Zr during the Variscan uranium mineralization event in high‐grade metasediments of the Bohemian Massif, Czech Republic has been investigated to understand their behaviour in alkaline hydrothermal alterations. The REE patterns together with high mobility of Y and Zr point to movement of REE, Y, Zr and U by highly mineralising, oxidising basinal fluids in the Permian. Their high mobility during the origin of an economically important uranium mineralization is supported by the occurrence of Y‐ and Zr‐rich coffinite. 相似文献
20.
Kinetics of zircon dissolution and zirconium diffusion in granitic melts of variable water content 总被引：2，自引：0，他引：2
The experimental dissolution of zircon into a zircon-undersaturated felsic melt of variable water content at high pressure in the temperature range 1,020° to 1,500° C provides information related to 1) the solubility of zircon, 2) the diffusion kinetics of Zr in an obsidian melt, and 3) the rate of zircon dissolution. Zirconium concentration profiles observed by electron microprobe in the obsidian glass adjacent to a large, polished zircon face provide sufficient information to calculate model diffusion coefficients. Results of dissolution experiments conducted in the virtual absence of water (<0.2% H2O) yield an activation energy (E) for Zr transport in a melt ofM=1.3 [whereM is the cation ratio (Na+K+2Ca)/(Al·Si)] of 97.7±2.8 kcal-mol?1, and a frequency factor (D 0) of 980 ?580 +1,390 cm2-sec?1. Hydrothermal experiments provide an E=47.3±1.9 kcal-mol?1 andD 0=0.030 ?0.015 +0.030 cm2-sec?1. Both of these results plot close to a previously defined diffusion compensation line for cations in obsidian. The diffusivity of Zr at 1,200° C increases by a factor of 100 over the first 2% of water introduced into the melt, but subsequently rises by only a factor of five to an apparent plateau value of ～2×10?9 cm2-sec?1 by ～6% total water content. The remarkable contrast between the wet and dry diffusivities, which limits the rate of zircon dissolution into granitic melt, indicates that a 50 μm diameter zircon crystal would dissolve in a 3 to 6% water-bearing melt at 750° C in about 100 years, but would require in excess of 200 Ma to dissolve in an equivalent dry system. From this calculation we conclude that zircon dissolution proceeds geologically instantaneously in an undersaturated, water-bearing granite. Estimates of zircon solubility in the obsidian melt in the temperature range of 1,020° C to 1,500° C confirm and extend an existing model of zircon solubility to these higher temperatures in hydrous melts. However, this model does not well describe zircon saturation behavior in systems with less than about 2% water. 相似文献