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1.
Amphiboles were synthesized from bulk compositions prepared along the join Ca1.8Mg5.2Si8O22(OH)2–Ca1.8Mg3Ga4Si6O22(OH)2 hydrothermally at 750–850 °C and 1.0–1.8 GPa, and along the join Ca2Mg5Si8O22F2–Ca2Mg3Ga4Si6O22F2, anhydrously at 1000 °C and 0.7 GPa to document how closely the tschermak-type substitution is obeyed in these analogues
of aluminous amphiboles. Electron-microprobe analyses and Rietveld X-ray diffraction structure refinements were performed
to determine cation site occupancies. The extent of Ga substitution was found to be limited in both joins, but with the fluorine
series having about twice the Ga content (0.6 atoms per formula unit, apfu) of the hydroxyl-series amphiboles (0.3 apfu).
The tschermak-type substitution was followed very closely in the hydroxyl series with essentially equal partitioning of Ga
between tetrahedral and octahedral sites. The fluorine-series amphiboles deviated significantly from the tschermak-type substitution
and, instead, appeared to follow a substitution that is close to a Ca-pargasite substitution of the type: [6]Ga3++2[4]Ga3++1/2[A] Ca2+ = [6]Mg2++2[4]Si4++1/2[A]□. Infrared spectroscopy revealed an inverse correlation between the intensity of the OH-stretching bands and the Ga content
for the hydroxyl- and fluorine-series amphiboles. The direct correlation between the Ga and F content and inverse relationship between the Ga and
OH content may be a general phenomenon present in other minerals and suggests, for example, that high F contents in titanite
are controlled by the Al content of the host rock and that there may be similar direct Al–F correlations in tschermakitic
amphiboles. Evidence for the possibility that Al (Ga) might substitute onto only a subset of the tetrahedral sites in tschermakitic
amphiboles was sought but not observed in this study.
Received: 5 March 2001 / Accepted: 31 July 2001 相似文献
2.
The granite collected from the Yinshan Mountain and kaolinite has been selected for the leaching and adsorption experiment,respectively,aiming to clarify the enrichment processes of Li and Ga during the deposition.Results suggest both Li and Ga could be leached out from granite by using different acid solutions of different p H and kaolinite can adsorb Li and Ga with varying degrees.Lithium and Ga had the highest leaching ratio when p H=1.Special geological events(e.g.volcanic eruptions and wildfires),which could result in very low p H values of water in peatland,may have accelerated the release of Li and Ga from the source rocks.Kaolinite has the highest adsorption fraction was obtained at p H=8.The different characteristics of Li and Ga displayed in the leaching and adsorption experiments probably result from the different occurrences and enrichment processes of Li and Ga in the coals.Lithium was probably enriched before the Li carriers(e.g.kaolinite)had been transported into paleomires because of its high leaching ratio and high adsorption fraction under neutral and alkaline conditions,whereas Ga was more likely concentrated by kaolinite and other carriers after it had been transported into the peat mires. 相似文献
3.
Gallium arsenide (GaAs) has both high saturated electron velocity and high electron mobility, making it useful as a semiconductor material in a variety of applications, including light‐emitting diodes (LEDs), integrated circuits (ICs), and microwave appliances. A side effect of the use of gallium (Ga) is the production of a relatively large amount of hazardous waste. This study aimed at the recovery of Ga and arsenic (As) from GaAs waste using hydrometallurgical methods involving leaching and coagulation and a dry annealing process that involves annealing, vacuum separation, and sublimation by heating. Our research has shown that GaAs can be leached using nitric acid (HNO3) to obtain 100% Ga and As with a leaching solution at pH 0.1, with subsequent adjustment of the leaching solution to pH 3 with sodium hydroxide (NaOH). Another method used a leaching solution at pH 2, then adjusting to pH 11 using NaOH. Ferric hydroxide (FeO(OH)) was added at 90°C after NaOH was added to the leaching solution. At pH 2 and 11, 55.5 and 21.9% of the As could be removed from the hazardous waste, respectively. The Ga could also be precipitated. When GaAs powder was heated to 1000°C over 3 h, 100% As removal was achieved, and 92.6% of the Ga was removed by formation of 99.9% gallium trioxide (Ga2O3). Arsenic was vaporized when the temperature was elevated to 1000°C, allowing arsenic trioxide (As2O3) to condense with 99.2% purity. The Ga2O3 powder produced was then dissolved and electrolyzed, allowing for 95.9% recovery of Ga with a purity of 99.9%. 相似文献
4.
E. Crété M. Giard L. Ravera J.-L. Noullet Ph. Bourdeu d'Aguerre M. Torrès J.-Y. Mayvial 《Experimental Astronomy》1998,8(3):239-255
We present the development of a correlator module intended for space borne high resolution heterodyne spectroscopy. Our attention has been focused on power consumption reduction (few mW per channel needed), while looking for a high clock frequency (few hundreds of MHz) to cover wide bandwidths. The module proposed, which may be the base of an hybrid analog/digital spectrometer, is composed of two full custom Very Low Scale Integration (VLSI) circuits using two different technologies: a high speed MEtal Semiconductor Field Effect Transistor (MESFET) on Gallium Arsenide substrate (GaAs) and a low power Complementary Metal Oxide Semiconductor (CMOS) on Silicon substrate (Si). A 0.8 m GaAs prototype circuit has been built and tested. It shows a correct global operation up to 242 MHz – and for marginal functions up to 611 MHz –, and a power consumption as expected by the simulations (less than 2 W). Expected improvements of the technology, together with some modifications developed here, demonstrate that a high frequency correlator module, meeting spatial requirements (many hundreds of channels and few mW per resolution point), should be feasible. 相似文献
5.
Although critical to newly evolving and increasingly essential technologies, antimony (Sb), gallium (Ga), and germanium (Ge) are generally recovered as byproducts or ‘companion metals’ of other metal ores. The stage at which companion metals are extracted depends on metallurgical processes by which the host ore mineral is extracted and processed; many companion metals are recovered late during this processing. Therefore, the current and future supply of companion metals relies not only on production of major commodities, but also on the efficient recovery of these metals during processing that recovers the primary commodity.National geological surveys, particularly the USGS, publish annual estimates of global reserves for a variety of primary metals, but generally not for companion metals. This study provides estimates for the geogenic stocks (in waste rock piles, tailings, smelting, and refining) of Ga, Ge, and Sb as companion metals. These elements are mined in Australia but may be recovered outside of Australia, but their life cycles have not yet been well understood.Based on the methodology adapted, this paper estimates a minimum of 970–1230 kt of Ga, 30–10,000 kt of Ge and 70–1000 kt of Sb in current Australian lead-zinc-silver, gold, copper, iron ore, coal, bauxite, and bauxite residue (red mud) resources. The large range of estimated stocks stems from the variable range of ore grades reported by companies and the considerable uncertainty that exists among the grade estimates presented. However, these estimates are reflective of best practice in mineral resource estimation of Ga, Ge, and Sb, and provide a basis for determining similar recoverable resource estimates of other companion metals, such as indium, rhenium, and selenium, all of which are of increasing importance in modern-day life. 相似文献
6.
煤炭是我国最主要的能源之一,如何高效开采开发和利用煤炭资源,是科学界的一个重要议题。受原生沉积条件影响,煤中可以含有多种共伴生矿产资源,部分共伴生矿产的价值甚至超过煤炭本身。山西省河东煤田是我国重要的优质炼焦煤生产基地,煤质好、煤炭储量巨大。在收集整理河东煤田煤中镓已有化验数据分析研究的基础上,分析了河东煤田煤中的镓分布规律和工业前景,发现河东煤田煤中镓在横向上总体呈现北高南低的趋势;纵向上,山西组煤中镓的含量显著高于太原组;在煤层内部,又存在垂向差异,即煤层下部煤中镓的含量高于上部煤中镓的含量。研究认为,物源区的距离是影响河东煤田煤中镓南北差异的一个重要因素;聚煤环境差异可能是影响河东煤田煤中镓含量差异的重要原因;原煤灰分差异可能是导致河东煤山西组和太原组煤层垂向差异的主要因素。从工业前景来看,河东煤田北中部矿区山西组下部地层煤中镓接近工业品位,具有一定开发潜力。 相似文献
7.
8.
The late Tertiary high ash brown coal (Rr=0.26%) of the Schirnding Seam Zone is mainly composed of huminite. The seam is underlain by a thick saprock (mica saprockkaolinite-mica saprock) some tens of meters thick which gradually developed from phyllitic basement rocks and a thin Footwall Series of coarse-grained clastic sediments which, however, occur only in a few places. The roof rocks ‘ Hanging Wall Series' abruptly appear on top of the seam and consist of massive gray mudstones and arenites, intercalated with some tuffites. These Tertiary series were studied in open-pit mines operated for coal and clay and in bore holes. Chemical investigation involved the analyses of TOC, TSC, Ni, Co, Pb, Zn, Ga, Be, V, Cr, U, Th, P, Zr, REE and organic compounds of extracted organic matter (=OM). Early Tertiary chemical weathering was responsible for the monotonous kaolinite-mica-goethite mineral assemblage in the saprock and the footwall series. In the coal-bearing basin a more variegated mineral association including, pyrite, kaolinite, illite, smectite, illite-smectite mixed layers and siderite was brought about by volcanic processes, intrastratal solution set free in course of coalification and early diagenesis and by meteoric waters infiltrating the coal-bearing series from uplifted parts of the basin, which underwent strong oxidation. The environment of deposition is interpreted in terms of peatswamps that were fed by small streams and crevasse splays of a meandering drainage system grading towards the basin margin into a braided stream system on an alluvial fan plain. Strongly fluctuating water levels were responsible for the pronounced cyclicity to be encountered across the coal-bearing series. The processes of element redeposition and element migration in the Schirnding Basin are operative across the interface coal-saprolite (detrital influx of heavy minerals and intrastratal solution, hydrocarbon infiltration and redistribution of organic matter, reworking of duricrusts), in the saprolite proper (weathering leachats) and across the redox boundaries between the Schirnding Seam Zone and the Hanging Wall Series (input of physils and diagenetic alteration) as well as its strongly oxidized stratigraphic equivalents at the basin edge (volcanic influx, intrastratal solutions). Chemical and mineralogical variations across the coal basin which are directly controlled by the variation in the environment of deposition, weathering and groundwater movements may be directly correlated to changes in the saprock due to the immediate contact between coal and bedrock. 相似文献
9.
Harford AJ Hogan AC Tsang JJ Parry DL Negri AP Adams MS Stauber JL van Dam RA 《Marine pollution bulletin》2011,62(3):466-473
Ecotoxicological studies, using the tropical marine diatom, Nitzschia closterium (72-h growth rate), were undertaken to assess potential issues relating to the discharge from an alumina refinery in northern Australia. The studies assessed: (i) the species’ upper thermal tolerance; (ii) the effects of three signature metals, aluminium (Al), vanadium (V) and gallium (Ga) (at 32 °C); and (iii) the effects of wastewater (at 27 and 32 °C). The critical thermal maximum and median inhibition temperature for N. closterium were 32.7 °C and 33.1 °C, respectively. Single metal toxicity tests found that N. closterium was more sensitive to Al compared to Ga and V, with IC50s (95% confidence limits) of 190 (140-280), 19,640 (11,600-25,200) and 42,000 (32,770-56,000) μg L−1, respectively. The undiluted wastewater samples were of low toxicity to N. closterium (IC50s > 100% wastewater). Environmental chemistry data suggested that the key metals and discharge are a very low risk to this species. 相似文献
10.
《地学前缘(英文版)》2023,14(4):101538
Gallium (Ga) is a critical mineral that plays an irreplaceable role in consumer electronics, clean energy technologies and the aerospace industry. Nowadays competition for gallium resources at the national strategic level has begun to emerge, but gallium resources are unevenly distributed globally, and their presence is not guaranteed. New discoveries revealed an average gallium concentration of thirty-one samples from M1, M2, M3 and M4 stone coal-bearing seams of the Cambrian strata on South Qinling Orogenic Belt in central China is 157 mg/kg (9.98–747 mg/kg), which is 27.6-fold higher than the global hard coal average, as well as the existing association of Mo–V–U–Cd–Zn–Ba–Se–Mg–Ni–Cu enrichment. Ga average of these coal seams are 344 mg/kg (M3, 44.5–747 mg/kg, n = 11), 270 mg/kg (M4, 14.3–270 mg/kg, n = 5), 53.8 mg/kg (M2, 22.6–75.4 mg/kg, n = 8) and 19.8 mg/kg (M1, 9.98–34.9 mg/kg, n = 7) respectively, as well as the thickness of approximately 6, 12, 8, and 20 m, which be close to or exceed to the boundary grade standard (30 mg/kg) and minimum recoverable thickness (0.7 m) of gallium resources exploration. These findings indicate that the Cambrian stone coal deposits, especially in the middle and late Cambrian period, should be considered as promising alternative sources of gallium. The anomalous gallium-enriched sediments originated from a complex combination of hydrothermal fluids, original biomass and terrigenous materials. For the M1 stone coal-bearing seams, gallium most likely occurred in the mode of GaAs, GaxIn1-xAs and GaO(OH), while modes of gallium in the M2 to M4 seams is interrelated with the organic affinity and clay minerals. The crude reserve estimate of gallium resources in central China is approximately 10.06 × 104 tons, corresponding to a super-large coal-hosted gallium ore deposit. The unique paleogeographic location and geological structure in central China resulted that this newly discovered deposit is a unique type of gallium-enriched deposit that has been discovered worldwide. These discoveries will provide the critical parameters when developing distinctive beneficiation processes and appropriate extraction procedures, as well as guidance and effective for future prospecting regions of gallium resources around the globe, involving a combination consider the distribution of regional deep–large fault zones and the middle to late Cambrian black rock series deposits. 相似文献