A method for synthesizing mullite powder at low temperature by molten salt method using coal gangue as raw material

Abstract

The invention relates to a method for performing low-temperature synthesis on mullite powder by adopting a molten salt method taking coal gangue as raw material. The method comprises the following steps: by taking coal gangue and crystalized aluminum potassium sulfate dodecahydrate as raw materials, weighing coal gangue and aluminum potassium sulfate dodecahydrate based on stoichiometric ratio of mullite and mixing the two, placing the mixture at 750-950DEG C and calcinating for 2-5 hours, then cooling to room temperature, washing the calcinated product with deionized water, and drying to obtain the mullite powder. The aluminum potassium sulfate dodecahydrate is both reaction raw materials and molten salt, and by adopting the aluminum potassium sulfate dodecahydrate, not only can the temperature of the mullite powder synthesized by adopting solid-phase method be effectively reduced, but also the content lack of aluminum in coal gangue can be supplemented. By controlling the reaction ratio, the calcinating temperature and time of the coal gangue and the molten salt, mullite powder with different microstructure and sizes can be obtained at low temperature (750-950DEG C). Not only does the preparation process be simple, the preparation cost is low, but also the purity of the obtained product is high, and the preparation process is easy for realization of industrial production.

Description

technical field [0001] The invention relates to a method for synthesizing mullite powder at a low temperature using coal gangue as a raw material molten salt method, in particular to a method capable of synthesizing orthorhombic mullite powder material at a relatively low temperature. Background technique [0002] Mullite is a high-quality refractory raw material, and this type of mineral is relatively rare. Mullite is a mineral formed by aluminosilicate at high temperature, and mullite will be formed when aluminosilicate is artificially heated. Natural mullite crystals are elongated needles in radial clusters. Mullite is used to produce high-temperature refractory materials. It has the characteristics of high load softening point, small high-temperature creep, stable volume, slag corrosion resistance, chemical corrosion resistance, thermal shock resistance and electrical insulation. Aluminum bricks are incomparable. Now mullite has been widely used in various thermal equ...

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Problems solved by technology

[0004] Domestic reports about the preparation of mullite powder by molten salt method are rare so far, and foreign related reports are also seldom. Zhang Bing et al. 2 SO 4 For molten salt, in the range of 1100 ~ 1300 ℃, using analytically pure Al 2 o 3 and SiO 2 Mullite is synthesized as a raw material, but the synthesis temperature of this method is high, the cost is high, and the process requirements are high, which is not conducive to actual production control

Nie Jianhua, Zhang Han, Xu Man, et al. Synthesis of mullite whiskers by molten salt method[J]. Rare Metal Materials and Engineering, 2009, 38 (Add 2): 1154-1157; Zhu Boquan, Li Xuedong, Hao Rui, et al .Study on thermodynamics of mullite synthesis in sodium sulfate molten salt[J].Acta Silicate Sinica, 2006, 34(1):76-80. The disadvantage of this type of system formulation is that it uses chemical raw materials to synthesize mullite Stone whisker has the disadvantage of high raw material cost

Chinese patent document CN 102312278 A adopts Al 2 (SO 4 ) 3 18H 2 O, Na 2 SO 4 Mix molten salt, and then wash with HF acid with a mass concentration of 20%, to obtain mullite whiskers with a relatively high length and diameter. It is 20% HF acid washing and purification, so it will cause the problem of secondary environmental water pollution

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