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5.1 The laboratory weathering procedure will generate data that can be used to: (1) determine whether a solid material will produce an acidic, alkaline, or neutral effluent, (2) identify solutes in the effluent that represent dissolved weathering products formed during a specified period of time, (3) determine the mass of solute release, and (4) determine the rate at which solutes are released (from the solids into the effluent) under the closely controlled conditions of the test.
5.2 Data generated by the laboratory weathering procedure can be used to address the following objectives: (1) determine the variation of drainage quality as a function of compositional variations (for example, iron sulfide and calcium+magnesium carbonate contents) within individual mine-rock lithologies, (2) determine the amount of acid that can be neutralized by the sample while maintaining drainage pH ≥ 6.0 under the conditions of the test, (3) estimate mine-rock weathering rates to aid in predicting the environmental behavior of mine rock, and (4) determine mine-rock weathering rates to aid in experimental design of site-specific kinetic tests.
5.3 The laboratory-weathering procedure provides conditions conducive to oxidation of solid material constituents and enhances the transport of weathering reaction products contained in the resulting weekly effluent. This is accomplished by controlling the exposure of the solid material sample to such environmental parameters as reaction environment temperature and application rate of water and oxygen.
5.4 Because efficient removal of reaction products is vital to track mineral dissolution rates during the procedure, laboratory leach volumes are large per unit mass of rock to promote the rinsing of weathering-reaction products from the mine-rock sample. A comparison of laboratory kinetic tests with field tests has shown that more reaction products from mineral dissolution are consistently released per unit weight and unit time in laboratory weathering tests (9). For example, sulfate release rates observed in laboratory tests of metal-mine rock have been reported to be 3 to 8 times those for small-scale field test piles of Duluth Complex rock (10), and from 2 to 20 times those for small-scale field test piles of Archean greenstone rock (11). A greater increase is anticipated when laboratory rates are compared with field rates measured from operational waste-rock piles.
5.5 Fundamental assumptions governing Options A and B of the procedure:
5.5.1 Option A—An excess amount of air pumped up through the sample during the dry- and wet-air portions of the weekly cycle reduces the potential for oxidation reaction rates being limited by low-oxygen concentrations. Weekly leaches with low ionic strength water promote the removal of leachable mineral dissolution products produced from the previous week's weathering cycle. The purpose of the three-day dry-air portion of the weekly cycle is t......
水冷型氙灯老化试验箱,通过光照加速老化,用于模拟材料在自然环境里的物理、化学改变,从而带来材料性能的各种变化,评估产品的使用寿命和优劣性。设备主要由工作室、光源、调温调湿人工降雨及其他辅助设施组成。满足国家和行业相关试验标准。...
二、热老化试验箱能更精确地反映湿和热对橡胶老化的双重作用结果: 1、对于一些对湿度敏感的材料; 2、无疑是提供了一种更准确的试验研究手段; 3、湿热老化试验箱目前存在的主要问题是试验结果的重现性较差; 4、主要原因在于相对湿度的波动、试样制备及具体试验操作方法等。 三、热老化试验箱适用于科研单位和工厂作可塑性材料(橡胶、塑料)、电气绝缘及其他材料的热老化试验。 ...
臭氧老化箱臭氧发生器采用高压无声放电管,高压无声放电管则可获得较高浓度的臭氧,试样老化箱室是封闭式的、无光照,箱门上开设了一个可以观察试样表面的窗口,试验箱外壳采用的是冷轧钢板静电喷塑,外形美观大方;箱室内壁、导管、试样夹具和结构材料等采用不易分解臭氧的不锈钢制造而成。...
用途:氙灯老化试验箱采用能摸拟全阳光光谱的氙弧灯来再现不同环境下存在的破坏性光波:1.可以为科研、产品开发和质量控制提供相应的环境模拟和加速试验。2.可用于新材料的选择、改进现有材料或评估材料组成变化后耐用性的变化试验。3.可以很好的模拟在不同环境条件下,材料暴露在阳光下所产生的变化。4.若试验样品不大或不多,建议使用台式氙灯,可以达到同样的效果。...
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