Papers by Keyword: Magnesia

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Authors: A.G.E. Sutjipto, T. Okamoto, Masasuke Takata
Authors: Christos G. Aneziris, Steffen Dudczig
Abstract: In terms of this work formulations of carbon bonded castables based on new binder approaches and nanoadditions will be demonstrated. The new binder system allows the manufacturing of water based magnesia carbon castables with the same properties and chemistry of pressed magnesia carbon bricks. This binder can be also applied in oxide castables offering them high refractoriness and workability during processing. According to the workability nano-additions improve significantly the spreading diameter of carbon castables and as a result their flowability.
Authors: Tatsuzo Nagai, Hae Jin Hwang, Masaki Yasuoka, Mutsuo Sando, Koichi Niihara
Authors: Nancy E. Quaranta, Marta G. Caligaris, Osmell Díaz
Abstract: The lining of steel converters and ladles consists of magnesia-graphite refractories. The steel industry is the biggest consumer of refractories, about 70% of the total production of these materials. For this reason, it is very important to recycle them for the production process. The aim of this work is to carry out the physicochemical and microstructural characterization of post-mortem magnesia-graphite refractories from a steel plant, in order to achieve their incorporation to the manufacture of ceramic masonry to be used in the construction industry. The obtained results indicate acceptable properties in these industrial wastes in relation to the physicochemical and environmental characteristics and the feasibility of reusing them in the mentioned applications.
Authors: Zhu Ding, Zong Jin Li, Feng Xing
Abstract: The magnesium phosphosilicate cement (MPSC) is a novel inorganic binder, it sets quickly and has very high strength. Also, it is a promising material for the sustainable development. In the present study, the durability of MPSC were investigated, including deicer scaling resistance under freezing-thawing cycles, chemical corrosion resistance in sodium sulfate and magnesium sulfate solutions, and wet-dry resistance in fresh and natural sea water. For comparison, Portland cement samples were also prepared for parallel tests. Test results showed that the chemical durability of MPSC is superior that of Portland cement. The causes of the high performance may be attributed to the low water demand and a reasonable microstructure of hardened paste matrix.
Authors: J.H. Yang, Sang Heum Youn, Jae Jun Kim, Kyu Hong Hwang, Sung Gap Lee, B.S. Jun, Seog Young Yoon, Jong Kook Lee, Hwan Kim
Abstract: To prevent the shrinkages by the densification during the application of unfired Al2O3-C refractories or Al2O3 castables in steel making conditions, MgO was added as aggregate or matrix powder and the expansion caused by spinel formation was studied. Because the spinel was formed at the contacting areas between Al2O3 and MgO particles and the volume of in-situ formed spinel increased more abnormally at the side of Al2O3 particles than MgO, the addition of MgO aggregates was not recommendable due to the formation of large voids around the MgO aggregates. Nevertheless, corrosion resistance was increased with the amount of fine MgO added, and the finer MgO powder added, the better residual expansion and minute structure formation was observed. In the contrary, in case of castables volume expansion due to spinel formation was not obvious because the degree of densification was less than high-pressure formed refractories. But CA6 phase would not form around alumina aggregates during corrosion so the corrosion resistance was much more enhanced.
Authors: Wen Zheng Zhang, Zheng Liu, Ping Li Mao
Abstract: Magnesia (MgO) is a fundamental component of many minerals found in nature and is used widely in our life, especially in refractory industry. However, the antihydration of MgO is a key concern in refractory suspension processing, MgO additions only in form of coarse particles(≥ 50 μm) or its contents of up to 10 wt.% are as a result of their high possibility to take place hydration reaction in water and the reaction can lead to volumetric expansion obviously. In the present work, citric acid (CA) can complex with Mg2+ in the MgO suspension under the condition of 4h and 25°C, and the deposit of magnesium ion-CA complexes become protective coating to inhibit magnesia react with water to form Mg(OH)2.The test results of RSV of different additives shows CA is the best antihydration compound to inhibit MgO hydration comparing with EDTA-2Na,sodium pyrophosphate(SP),trimeric sodium phosphate(TSP), which RSV is only 5.3ml when its dosage is 0.3%wt.
Authors: Qian Qian Wang, Xiao An Li, De Zhou Wei, Shu Juan Dai
Abstract: Magnesia is a widely used inorganic chemical product. magnesite is an advantageous resource in China, and also an important source of magnesia. There are tree methods to making magnesia from magnesite using heat treatment. They are light burning, dead burning and melt. In recent years, domestic researches have been done on processes, product performance and process mechanism of these methods.
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