MANUFACTURE OF COPPER FINE POWDER

PURPOSE:To manufacture high quality copper fine powder having uniform particle diameter and small diameter by reacting cuprous oxide having high chlorine grade with acid and executing chemical reduction treatment after executing disproportionation. CONSTITUTION:After executing the disproportionation by reacting the cuprous oxide having >=0.02 chlorine grade with the sulfuric acid, this slurry is washed to make about 0.05g/l of copper ion. The metallic copper concn. in the disproportionated treating material (metallic copper, copper sulfate, etc.,) in the slurry after washing is adjusted to about 20 - 50g/l and pH is made to about 13.0 - 13.5 and hydrazinium sulfate is used at about 1 - 10g/l of the slurry and the chemical reduction treatment is executed at about 10 - 30 deg.C liquid temp. Successively, a large part of alkali is removed with decantation and after making about 0.5 - 1.0 of the pH with acid, this is washed to about 2 - 3 of the pH with ion exchanging water. Further, after applying rust preventing film in the water by treating with the ion exchanging water including rust preventing agent, again this is washed to neutral of the pH with the ion exchanging water and separated to solid and liquid and dried with hot blast. By this method, the high quality copper fine powder being useful to conductive paste is obtd.