First, the process.

Figure 1.

Production Process 1 Fire bismuth oxide FIG.

Second, the main technical conditions.

The No. 1 fine enthalpy is melted and slowly added into a water quenching tank to be quenched into loose porous particles having a particle size of 5 mm or less.

Nitric acid dissolution: The volume of nitric acid is diluted twice with distilled water, and water quenching is added at normal temperature. The reaction is:

Bi+4HNO 3 =Bi(NO 3 ) 3 +NO+2H 2 O

In order to prevent a large amount of nitrogen oxides from escaping, water quenching should be added slowly. The solution after the reaction is a cerium nitrate solution.

Concentrated crystal: The concentration temperature is controlled at about 100 ° C, the volume of the solution is evaporated to 50% and the crystal is cooled. After 10 hours, 60% to 70% of the cerium nitrate contained in the solution is crystallized out; after the precipitated cerium nitrate crystal is separated, The mother liquor is concentrated again, the volume is doubled, and 20-30% of cerium nitrate crystals are obtained. The impurities are all left in the second mother liquor, and the second mother liquor is heated and treated with water to form a basic cerium nitrate precipitate. (OH) 2 NO 3 is filtered and then returned to dissolve with nitric acid: the precipitated cerium nitrate crystals are washed with a small amount of acid-containing water (H 2 O:HNO 3 =5:2), and air-dried at room temperature, which releases part of the nitrogen. Oxide tail gas.

Calcination: The temperature is controlled at about 600 ° C, and the burning time is 3 to 4 hours, at which time a large amount of nitrogen oxide gas escapes. The response is:

4Bi(NO 3 ) 2 =2Bi 2 O 3 +12NO 2 +3O 2

After calcination until nitrogen oxides escaped, the temperature was lowered, and the calcined cerium oxide was taken out and pulverized to a particle size of 60 mesh using a ceramic ball mill .

Third, the main equipment.

One muffle electric furnace; one porcelain ball mill.


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