PURPOSE: To suppress gassing in a negative electrode to increase electrolyte leakage resistance by magnetically refining amalgamated zinc powder by making pass through a strong magnetic field having a flux density of 15,000 gauss formed by a electromagnet comprising a core of a soft magnet having high saturation flux density.
CONSTITUTION: Zinc powder is put into a stainless steel container and a potassium hydroxide solution is added, and they are stirred with a stainless steel ribbon stirrer, then mercury having a purity of 99.7wt%, and containing less than 0.003wt% nitric acid and less than 0.003wt% Fe is added and stirred to obtain amalgamated zinc powder (ratio of amalgamation is 5%). This amalgamated zinc powder is sprinkled over the core end of an electromagnet having a flux density of 15,000 gauss or more and treated for about 2min. Zinc powder fallen from the magnet is collected. This treatment is repeated three times and obtained zinc powder is used to form a negative electrode 5.
OOHIRA TSUKASA
TAKADA KANJI
KUMANO YASUYUKI
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