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首页> 外文期刊>Journal of Volcanology and Geothermal Research2012V243-244NOCT,15 >Mineralogical and thermal characterization of a volcanic ash: Implications for turbine interaction
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Mineralogical and thermal characterization of a volcanic ash: Implications for turbine interaction

机译：火山灰的矿物学和热表征：涡轮互动的影响

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摘要

Volcanic ash (grain size 2 mm) is a ubiquitous product of explosive volcanic activity. Substantial input of volcanic ash into the atmosphere can lead to repetitive chronic global climate effects whose atmospheric impacts may have durations of up to years. In addition, several recent incidents document the acute hazard potential of volcanic ash interacting with infrastructure supporting technologies. One prominent example is the interaction of volcanic ash with operational jet engine turbines in commercial and/or military aviation.The physico-chemical and phase state of ash influences substantially the thermal behavior of volcanic ash and our ability to predict that behavior and therefore depends on reliable characterization of this state. Here, we have investigated the chemical composition and mineralogy (phase state) of fresh volcanic ash from Tungurahua volcano, Ecuador, as a function of grain size (below 180 mu m) in order to evaluate differences between ground-sampled ash and airborne ash, interacting with jet engines. For the sieved grain size fractions (down to 20 mu m) no significant grain size dependence of ash state is observable. At the 10 mu m (PM10) fraction, the influence of the separation and handling procedures requires special attention. A single-stage separation method, using a 20 mu m pre-sieved ash as source material, shows no grain size dependence of the phase state whereas the use of the unsieved original ash as source material results in an enrichment of plagioclase and a depletion of glass. In contrast, a multi stage gravitational separation procedure, using the unsieved original ash as source material, leads to an enrichment in the glassy phase and a depletion in all crystalline mineral phases. We thus infer that the phase state of the PM10 fraction strongly depends on the choice of starting material and the separation procedure.Using an optical dilatometer image analysis, we have characterized the thermal behavior of the volcanic ash upon heating, which we parameterize in terms of four characteristic temperatures. Using these data the determination of the flow temperature is refined to improve measurement accuracy for fine-grained (63 mu m) volcanic ash. (C) 2019 Elsevier B.V. All rights reserved.
机译：火山灰（晶粒尺寸<2 mm）是一种易受爆炸性火山活性的普遍存在的产物。大气进入大气中的大量投入可能导致重复的慢性全球气候影响，其大气影响可能具有多年的持续时间。此外，最近的几个事件记录了与基础设施支持技术相互作用的火山灰的急性危害潜力。一个突出的例子是火山灰与商业射流发动机涡轮机的相互作用在商业和/或军用航空中。灰分的物理化学和相位状态影响火山灰的热行为以及我们预测该行为的能力，因此取决于这种状态的可靠特征。在这里，我们研究了来自古福纳火山，厄瓜多尔的新鲜火山灰的化学成分和矿物学（相状态），作为粒度（低于180 mu m）的函数，以评估地面采样灰和空气灰烬之间的差异，与喷气发动机互动。对于筛分粒度分数（低至<20μm），无明显的灰色状态依赖性的显着晶粒尺寸。在<10μm（pm10）分数下，分离和处理程序的影响需要特别注意。单级分离方法，使用<20μm预筛分的灰作为源材料，显示出相位状态的晶粒尺寸依赖性，而未被取出的原始灰分的使用导致源材料的富集和耗尽玻璃。相反，使用未发现的原始灰分作为源材料的多级重力分离过程导致玻璃相中的富集和所有结晶矿物相中的耗尽。因此，我们推断PM10分数的相位状态强烈取决于起始材料的选择和分离程序。光膨胀计图像分析，我们已经表征了在加热时的火山灰的热行为，我们参数化四个特征温度。使用这些数据，改进了流动温度的测定，以提高细粒（<63μm）火山灰的测量精度。 （c）2019 Elsevier B.v.保留所有权利。

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