Methods for chemical analysis of zinc oxide produced by direct process -
Part 6: Testing of metallic zinc
1 Scope
This part of GB/T 4372 specifies the methods for testing metallic zinc in zinc oxide produced by direct process.
This part is applicable to the testing of metallic zinc in zinc oxide produced by direct process. The lower detection limit shall be: ≥0.065% for metallic zinc; ≥0.008% for metallic aluminum.
2 Method summary
Mix the specimen and anthraquinone evenly, add the sodium hydroxide solution, stir it until it becomes pasty, and heat it. The specimen will show wine red spots if it contains metallic zinc, by which the presence of metallic zinc may be tested. The same reaction is also available for metallic aluminum, so the testing result obtained by this method is taken as the total content of metallic zinc and metallic aluminum. Sulfite, sulfide, thiosulfate, metallic iron, etc. do not affect the testing.
3 Reagents
3.1 Anthraquinone (ground into powder in mortar before use).
3.2 Sodium hydroxide solution: 200g/L.
4 Apparatus
30mL glass dish with a bottom diameter of about 50 mm.
5 Specimen
5.1 The specimen shall have a particle size smaller than 0.10 mm.
5.2 Parch the specimen at 100℃~105℃ for 2h, after that, cool it to ambient temperature in a desiccator.
