Process for preparing mullite whisker or flaky alumina by using coal ash

A mullite whisker and flaky alumina technology, which is applied in the direction of single crystal growth, crystal growth, single crystal growth, etc., can solve the problems of inability to realize high value-added utilization of waste and high cost of raw materials, and achieve low cost and high efficiency. Strong, high-purity effects

Inactive Publication Date: 2010-07-14
SHAANXI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The cost of raw materials used in the above existing preparation meth

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0025] Example 1

[0026] Use a ball mill to grind the fly ash into 10 g of fly ash fine powder with a particle size of 0.1 μm, and add aluminum sulfate or silica fume according to the chemical composition of the fly ash (to make Al in the mixture 2 o 3 , SiO 2 The molar ratio is 1:0.5), then add sodium sulfate (the content in the mixture is 20%, mass ratio), mix the mixture uniformly in a ball mill, put it into a crucible with a cover, and react at 800°C for 5h. Soak the calcined sample product in water at 40°C for 24h, filter and wash it, then soak it in a hydrofluoric acid solution with a temperature of 20°C and a concentration of 40wt% for 10h, filter, wash, and dry to obtain mullite whiskers .

Example Embodiment

[0027] Example 2

[0028] Use a ball mill to grind the fly ash into 10 g of fly ash fine powder with a particle size of 80 μm, and add aluminum hydroxide or amorphous silicon oxide according to the chemical composition of the fly ash (to make the Al in the mixture 2 o 3 , SiO 2 The molar ratio is 1:1), then add potassium sulfate (in the mixture, its content is 60%, mass ratio), after the mixture is mixed uniformly in a ball mill, put it into a crucible with a cover, and react at 1300°C for 0.5h . The calcined sample product was soaked in 100°C water for 3h, filtered and washed, then soaked in a hydrofluoric acid solution with a temperature of 60°C and a concentration of 10wt% for 1h, filtered, washed, and dried to obtain mullite whiskers .

Example Embodiment

[0029] Example 3

[0030] Use a ball mill to grind the fly ash into 10 g of fly ash fine powder with a particle size of 60 μm, and add alumina or silica fume according to the chemical composition of the fly ash (to make Al in the mixture 2 o 3 , SiO 2 The molar ratio is 1:0.6), then add sodium chloride (in the mixture, its content is 30%, mass ratio), after the mixture is mixed uniformly in a ball mill, put it into a crucible with a cover, and react at 1000°C for 3h . The calcined sample product was soaked in 80°C water for 5h, filtered and washed, then soaked in a hydrofluoric acid solution with a temperature of 40°C and a concentration of 20wt% for 3h, filtered, washed, and dried to obtain mullite whiskers .

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Abstract

The invention discloses a process for preparing mullite whisker or flaky alumina by using coal ash. The process comprises the following steps of: grinding coal ash into powder, adding an additive containing aluminum or silicon, adding a fused salt additive, and uniformly mixing; loading the mixture into a crucible with a cover, reacting under a setting temperature, washing to remove dissoluble salt with hot water, dissolving impurity phase in the sample with hydrofluoric acid solution, washing and drying to obtain the mullite whisker or the flaky alumina. The method has the characteristics of simple process and easy industrial production, and by adopting the method, the coal ash can be reused and utilized. The mullite whisker or the flaky alumina prepared by the invention can be used as reinforcement in composite materials to improve the strength, the toughness and the heat-resisting performance of the composite material, and can be widely applied in the fields of aviation, automobiles, kilns and the like. The prepared flaky alumina also can be used as abrasives, pearl pigments, fillings and the like.

Description

technical field [0001] The invention relates to a preparation process of mullite whiskers or flaky alumina, in particular to a process for preparing mullite whiskers or flaky alumina with fly ash. Background technique [0002] Fly ash is solid waste discharged from thermal power plants, and the main chemical composition of fly ash is Al 2 o 3 and SiO 2 . my country's fly ash emissions exceed 100 million tons per year, and the world's emissions are 5 billion tons per year. Among the discharged fly ash, less than 1 / 2 of the fly ash is used for low value-added applications such as cement production, coal pit filling, and civil engineering, and the rest is piled up in ash dams, so the utilization rate of fly ash is low . [0003] Mullite, also known as mullite, is an aluminosilicate mineral, which was first discovered in Mull Island, Scotland in 1924 [Journal of the European Ceramic Society, 2008, 28: 329-344], although the aluminum on the crust , silicon and oxygen elemen...

Claims

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Application Information

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IPC IPC(8): C30B29/62C30B29/34
Inventor 谭宏斌郭从盛傅明星
Owner SHAANXI UNIV OF TECH
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