Magnesium oxide particle aggregate

A technology of aggregates and magnesia, applied in magnesia, furnaces, heat treatment equipment, etc., can solve the problems that it is difficult to apply and cannot properly evaluate forsterite

Inactive Publication Date: 2004-01-28
TATEHO CHEM IND CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, only very small values, such as 0.1×10 -6 Micropores below m, it is difficult to apply to the 1×10 observed in the actual magnesium oxide particle aggregates -5 ~1×10 -6 In the particle aggregation structure of about m size, forsterite formation reaction cannot be properly evaluated

Method used

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Examples

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Embodiment 1

[0062] At a concentration of 2.0mol·kg -1 Add potassium hydroxide slurry to the magnesium chloride solution, so that the concentration of magnesium hydroxide after the reaction is 1.2mol kg -1 , the mixed solution was reacted in an autoclave at 150°C for 3 hours to obtain a BET specific surface area of ​​8.2×10 3 m 2 kg -1 of magnesium hydroxide. Using a rotary kiln at temperatures of 800°C, 950°C, and 1050°C, respectively, firing for 1 hour and then pulverizing with an impact mill to produce three kinds of aggregates of magnesium oxide particles with different degrees of firing. Afterwards, in order to make the particle aggregation form fall within the scope of the present invention, the three kinds of magnesium oxide particle aggregates were mixed at a mixing ratio of 30:40:30 to obtain magnesium oxide particle aggregates.

Embodiment 2

[0064] Using a rotary kiln, magnesite was fired at 1100°C for 1 hour to obtain a BET specific surface area of ​​5.2×10 3 m 2 kg -1 of magnesium hydroxide. Add the magnesium oxide to water, and make the slurry concentration 2mol·kg -1 , and reacted at 90°C for 2 hours to obtain a BET specific surface area of ​​7.5×10 3 m 2 kg -1 of magnesium hydroxide. Then, they were fired in a rotary kiln at 980° C. for 0.2 hours, 0.5 hours, 0.8 hours, and 2 hours, respectively, and then pulverized with an impact mill to obtain aggregates of magnesium oxide particles with different degrees of firing. Afterwards, in order to make the particle aggregation form fall within the scope of the present invention, the four kinds of magnesium oxide particle aggregates were mixed at a mixing ratio of 25:30:15:30 to obtain the magnesium oxide particle aggregate of Example 2.

Embodiment 3

[0066] Add slaked lime to the brine so that the concentration of magnesium hydroxide after the reaction is 1.2mol kg -1 , and stirred at 600 rpm, and reacted at 80° C. for 2 hours. Then, the magnesium hydroxide obtained by filtering, washing and drying with a filter press was fired at 900°C for 1 hour in a rotary kiln to obtain a BET specific surface area of ​​20.6×10 3 m 2 kg -1 of magnesium hydroxide. Add the magnesium oxide to water, and make the slurry concentration 3mol·kg -1 , then add magnesium chloride relative to magnesium oxide 2mol%, and react the mixed solution at 80°C for 2 hours to obtain a BET specific surface area of ​​11.0×10 3 m 2 kg -1 of magnesium hydroxide. Next, use a muffle furnace to burn at a furnace temperature of 1200°C for 2 hours, 3 hours, and 4 hours, respectively, and then pulverize with an impact mill to obtain magnesium oxide particles with different firing degrees. Aggregates. Then, in order to make the particle aggregation form fall ...

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Abstract

An aggregate of magnesium oxide particles, characterized by exhibiting a cumulative pore volume curve which satisfies that the pore diameter at the first inflection point is greater than 0.30 x 10<-6> m and not greater than 0.30 x 10<-6> m or the void volume between the particles is not less than 0.80 x 10<-3>m<3> and less than 1.40 x 10<-3>m<3>-kg<-1>, and that the void volume inside the particles is 0.50 x 10<-3> to 0.90 x 10<-3>m<3>-kg<-1> and the volume of fine pores in the particles is 0.04 x 10<-3> to 0.11 x 10<-3>m<3>-kg<-1>. The aggregate of magnesium oxide particles can be used for suitably controlling the solid-solid reaction of magnesium oxide with a SiO2 film on the surface of a steel.

Description

technical field [0001] The present invention relates to a magnesia particle aggregate with controlled particle aggregation structure, and more particularly to a magnesia particle aggregate for an annealing separator for forming a forsterite coating that imparts excellent insulating properties and magnetic properties to a grain-oriented electrical steel sheet. Background technique [0002] Grain-oriented electrical steel sheets used in transformers or generators are usually hot-rolled silicon steel with a Si content of about 3%, and then cold-rolled to the final plate thickness, followed by decarburization annealing (primary recrystallization annealing), finish annealing And made. At this time, in order to impart insulation to the electrical steel sheet, a slurry containing magnesia is coated on the surface of the decarburization-annealed steel sheet, dried, coiled, and then finished annealed. In decarburization annealing, Si contained in the steel sheet reacts with oxygen t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F5/02H01F1/18
CPCC01P2006/14C01P2006/16C21D8/1283H01F1/18C01P2004/50C01F5/02C23C22/00
Inventor 东塚淳生平津丰
Owner TATEHO CHEM IND CO
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