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低活性氧化镁是制备磷酸镁水泥(MPC)的关键原材料。现行低活性氧化镁的生产方式导致了制备MPC具有能耗高和成本高的缺点,不利于其推广应用。利用盐湖中常见元素如B,Na、K和Cl的助烧结作用,在≤1 200℃煅烧盐湖提锂镁渣、外掺B的轻烧镁粉和水氯镁石的热解产物制备低活性氧化镁。介绍了低活性氧化镁的粒径、比表面积、孔隙率、化学组成、矿物组成和形貌等物理特征,以及低活性氧化镁制备MPC的凝结时间、水化产物、微观结构、抗压强度、体积稳定性等凝结硬化性能,并分析了烧结温度对低活性氧化镁的理化性能及MPC的凝结硬化性能的影响。相比现有技术,利用盐湖共存元素的助烧结作用可将氧化镁的烧结温度由1 500~1 800℃降低到1 200℃以下,有利于实现低活性氧化镁及MPC的低能耗、低成本绿色制备,促进MPC的推广应用。 相似文献
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《Chemie der Erde / Geochemistry》2019,79(4):125524
Due to their common occurrence in various types of chondrites, igneous rims formed on pre-existing chondrules throughout chondrule-forming regions of the solar nebula. Although the peak temperatures are thought to reach similar values to those achieved during chondrule formation events, the heating duration in chondrule rim formation has not been well defined. We determined the two-dimensional chemical and oxygen isotopic distributions in an igneous rim of a chondrule within the Northwest Africa 3118 CV3oxA chondrite with sub-micrometer resolution using secondary ion mass spectrometry and scanning electron microscopy. The igneous rim experienced aqueous alteration on the CV parent body. The aqueous alteration resulted in precipitation of the secondary FeO-rich olivine (Fa40–49) and slightly disturbed the Fe-Mg distribution in the MgO-rich olivine phenocrysts (Fa11–22) at about a 1 μm scale. However, no oxygen isotopic disturbances were observed at a scale greater than 100 nm. The MgO-rich olivine, a primary phase of igneous rim formation, has δ17O = −6 ± 3‰ and δ18O = −1 ± 4‰, and some grains contain extreme 16O-rich areas (δ17O, δ18O = ∼−30‰) nearly 10 μm across. We detected oxygen isotopic migration of approximately 1 μm at the boundaries of the extreme 16O-rich areas. Using oxygen self-diffusivity in olivine, the heating time of the igneous rim formation could have continued from several hours to several days at near liquidus temperatures (∼2000 K) in the solar nebula suggesting that the rim formed by a similar flash heating event that formed the chondrules. 相似文献
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用WB和JC标准水合法测定轻烧MgO粉的活性MgO含量,对测定结果进行方差和误差分析,并研究了水化时间对测定结果的影响。结果表明,两种方法存在显著性差异,WB和JC水合法的平均相对误差分别为1.31%和-19.85%,WB水合法精密度远高于JC水合法。以WB水合法为基准,JC水合法的平均相对误差大于-20%,远远超过行业标准中规定的±3%。因此,对于镁水泥原料MgO中活性含量的定量分析,不能采用JC方法,必须采用WB方法。此外,发现水化3 h已经接近活性氧化镁的水化平衡,为修订WB标准方法提供了参考依据。 相似文献
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Fog and rain water chemistry at Mt. Fuji: A case study during the September 2002 campaign 总被引:2,自引:0,他引:2
Koichi Watanabe Yusaku Takebe Nobuhiro Sode Yasuhito Igarashi Hiroshi Takahashi Yukiko Dokiya 《Atmospheric Research》2006,82(3-4):652
Measurements of fog and rain water chemistry at the summit of Mt. Fuji, the highest peak in Japan, as well as at Tarobo, the ESE slope of Mt. Fuji in September 2002. The pH of fog and rain water sampled at Mt. Fuji varied over a range of 4.0–6.8. Acidic fogs (pH < 5.0) were observed at the summit when the air mass came from the industrial regions on the Asian continent. The ratio of [SO42−]/[NO3−] in the fog water was lower at Tarobo than at the summit. High concentrations of Na+ and Cl− were determined in the rain water sampled at the summit, possibly because of the long-range transport of sea-salt particles raised by a typhoon through the middle troposphere. The vertical transport of sea-salt particles would influence the cloud microphysical properties in the middle troposphere. Significant loss of Mg2+ was seen in the rain water at the summit. The concentrations of peroxides in the fog and rain water were relatively large (10–105 μM). The potential capacity for SO2 oxidation seems to be strong from summer to early autumn at Mt. Fuji. The fog water peroxide concentrations displayed diurnal variability. The peroxide concentrations in the nighttime were significantly higher than those in the daytime. 相似文献
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