石棉尾矿制备轻质氧化镁的工艺条件研究

以石棉尾矿为原料,对制备轻质氧化镁的工艺条件进行了优化选择。以硫酸浸矿,在矿物粒度为80目,酸用量为理论值的120%,液固比为4∶1,反应温度为(95±2)℃,反应时间为1 h的条件下,镁的浸出率可达81.74%;采用多效分离剂,在pH值为5.5~6.5时分离杂质铁,经碳酸钠水溶液沉淀的碳酸镁,在850℃焙烧2.5 h,其轻质氧化镁的纯度达到99.3%,为石棉尾矿的综合利用提供了一条新的途径。     

煅烧条件对石棉尾矿酸浸出率的影响及机理研究

为提高石棉尾矿的酸浸出率,采用静态加热法对石棉尾矿样品进行了煅烧处理,研究了煅烧条件对石棉尾矿煅烧产物酸浸出率的影响及机理。采用热分析、XRD、红外光谱分析对原样及煅烧产物的结构、物相及分子振动吸收光谱的变化进行了分析和表征。揭示了煅烧温度、煅烧时间对石棉尾矿煅烧产物的结构、物相和酸浸出率的影响及机理。结果表明,在煅烧过程中,石棉尾矿中的纤蛇纹石先失去氢氧镁石层的外羟基,然后失去内羟基,同时伴随着镁橄榄石的结晶作用,至纤蛇纹石结构整体分解达到完全后,产物的酸浸出率才达到最高。获得最高酸浸出率的煅烧活化条件为煅烧温度680℃,煅烧时间40 min。     

硫酸铵与粉煤灰焙烧产物的物相组合及变化规律

为了提取粉煤灰中的Al2O3,采用助剂硫酸铵与粉煤灰混合,并经焙烧处理形成易浸取的硫酸铝铵。利用TG-DTA、XRD等分析手段对焙烧反应产物进行表征,研究了助剂添加量、焙烧温度、焙烧时间对焙烧产物的影响。结果表明:添加硫酸铵焙烧可将粉煤灰中的Al2O3以硫酸铝铵的形式释放出来;当n(Al2O3)∶n[(NH4)2SO4]=1∶6时,粉煤灰中莫来石相完全消失;焙烧时间超过1.5 h时,其对应焙烧产物的物相主要为硫酸铝铵;升高温度,有利于硫酸铝铵的形成。     

石棉尾矿硫酸铵焙烧法提取氧化镁制备碱式碳酸镁的实验研究

基于石棉尾矿中富含氧化镁组分的特点,在矿物学特征研究基础上,采用硫酸铵焙烧法提取氧化镁,利用浸出液硫酸镁制备碱式碳酸镁。采用XRD、SEM、FT-IR和TG-DTA对不同温度条件下所获得的产物的物相、形貌、分子振动光谱和热效应变化等特征进行了分析和表征。结果表明:利用硫酸铵焙烧产物的浸取液,在低于65℃的水溶液中所制备的产物为针状水合碳酸镁;在高于85℃时制备的产物为片状碱式碳酸镁;在75℃温度时形成短柱状或颗粒状水合碳酸镁和片状碱式碳酸镁的混合物。对水合碳酸镁加热,在100℃脱去部分水合水和二氧化碳后转变为片状碱式碳酸镁。研究结果对石棉尾矿的资源化利用和环境保护具有一定的理论和实际意义。     

红土镍矿中镁橄榄石在高浓度氢氧化钠中的浸出过程

根据红土镍矿中镁橄榄石的存在形式,采用高温固相法合成Mg2SiO4,通过正交试验优化Mg2SiO4在高浓度氢氧化钠中的浸出过程,利用XRD对浸出反应渣进行物相分析,探讨了液固比、氢氧化钠浓度、反应时间和反应温度对Mg2SiO4中SiO2的浸出率的影响。结果表明:Mg2SiO4在高浓度氢氧化钠中浸出过程优化实验条件为,反应温度220℃,反应时间120min,液固比6∶1,NaOH浓度85%;浸出反应渣的XRD分析结果表明:NaOH介入硅酸盐晶格中,其中间产物为Na2MgSiO4,Mg2+经过碱熔融过程可以脱离SiO4阵列,以Mg(OH)2形式从其硅酸盐中得以释放。     

红土镍矿中镁橄榄石在高浓度氢氧化钠中的浸出过程北大核心CSCD

根据红土镍矿中镁橄榄石的存在形式,采用高温固相法合成Mg2SiO4,通过正交试验优化Mg2SiO4在高浓度氢氧化钠中的浸出过程,利用XRD对浸出反应渣进行物相分析,探讨了液固比、氢氧化钠浓度、反应时间和反应温度对Mg2SiO4中SiO2的浸出率的影响。结果表明:Mg2SiO4在高浓度氢氧化钠中浸出过程优化实验条件为,反应温度220℃,反应时间120min,液固比6∶1,NaOH浓度85%;浸出反应渣的XRD分析结果表明:NaOH介入硅酸盐晶格中,其中间产物为Na2MgSiO4,Mg2+经过碱熔融过程可以脱离SiO4阵列,以Mg(OH)2形式从其硅酸盐中得以释放。     

煤系高岭土制取高纯氧化铝——萃取除铁

煤系高岭土焙烧活化后与硫酸铵反应,水浸取得到硫酸铝铵溶液,再采用磷酸二异辛基酯(P204)-N,N-甲基庚乙酰胺(N503)混合萃取剂除铁;与碳酸氢铵共沉淀制取碳酸铝铵(AACH)结晶后热解煅烧,制得高纯超细氧化铝.讨论了用N503-P204混合萃取剂进行三级逆流萃取时,水相pH值和萃取时间等操作条件对萃铁效果的影响;用TG-DTA研究了前驱物的热解特性,用XRD、TEM表征了AACH及其煅烧产物的物相及粒径;用ICP测定了煅烧产物的纯度.分析结果表明,铁的萃取率达到99.2%,AACH的纯度满足制取高纯超细Al2O3的要求.产品为粒径小于70 nm、纯度大于99.95%的Al2O3.     

某锡铁矿尾矿脱铍回收工艺研究

本研究以某锡铁矿尾矿为试验原料,采用高温焙烧-硫酸浸出工艺脱除尾矿中的有毒金属元素铍,考察了焙烧温度、焙烧助剂、浸出时间、浸出温度、液固比、焙烧时间、硫酸浓度等因素对尾矿中铍浸出率的影响.结果表明:尾矿经950℃高温焙烧2h后,以质量浓度30％硫酸作浸出剂,液固比4:1,在90℃高温条件下浸出6h,可获得铍浸出率86....     

高钛型高炉渣与硫酸铵焙烧过程中反应产物的变化与形成机理研究

高钛型高炉渣富含TiO₂,是一种重要的矿物资源。为实现其中TiO₂的富集,研究了其与硫酸铵的混合物在焙烧过程中反应产物的变化及形成机理。采用TG-DTA和XRD对高钛型高炉渣与硫酸铵混合物的热效应变化和原料及焙烧产物的物相组成进行了表征。结果表明,高钛型高炉渣主要矿物组成为钙钛矿、透辉石和镁铝尖晶石,其与硫酸铵的混合物在加热过程中存在3个明显的吸热效应,为硫酸铵自身分解反应及与高钛型高炉渣中金属氧化物的反应和所形成的中间产物的分解反应所引起。在较低的焙烧温度下,硫酸铵分解产物为(NH₄)₃H(SO₄)₂,其与钙钛矿和透辉石中的金属氧化物反应可形成CaSO₄;在焙烧温度为300～375℃时,镁铝尖晶石中的Al₂O₃与(NH₄)₂SO₄和(NH₄)₃H(SO₄)₂反应形成(NH₄)₃Al(SO₄)₃;在375～425℃时,(NH₄)₃Al(SO₄)₃与Al₂O₃反应形成NH₄Al(SO₄)₂;焙烧温度升高至500℃时,NH₄Al(SO₄)₂发生分解生成Al₂(SO₄)₃。     

阿克塞石棉尾矿矿物学特征及开发利用研究

采用XRF、XRD和SEM对阿克塞红柳沟矿区的石棉尾矿进行了矿物学特征分析,并进行了制备含硅、镁系列化合物的开发研究。结果表明: 3个矿山石棉尾矿样品的主要化学组成为SiO₂ 37.01%～39.35%,MgO 37.00%～38.92%,其次是TFe₂O₃ 6.02%～8.37%,烧失量为12.29%～13.56%;主要矿物组成为蛇纹石,且含少量滑石、磁铁矿、水镁石、菱镁矿。石棉尾矿经酸浸获得硫酸镁,制备了"卡房状"氢氧化镁、片状碱式碳酸镁及"卡房状"氧化镁粉体;石棉尾矿的酸浸渣经碱浸获得偏硅酸钠,制备了球状纳米级白炭黑。研究结果对阿克塞红柳沟矿区的石棉尾矿的资源化利用和环境保护具有一定的理论和实际意义。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)