A method of leaching a precious metal contained in decopperized anode slime includes, agitating and circulating a slurry at the same time, in carrying out hydrochloric acid oxidation leaching of the precious metal contained in the decopperized anode slime by adding a hydrochloric acid and an oxidant to the slurry of the decopperized anode slime, wherein in the circulating, the slurry is extracted from a lower portion of a tank and supplied again into an upper portion of the tank.

A method of producing a refined copper includes depositing the refined copper on a cathode by an electroplating process or an electroless plating process in an alkaline plating bath including a solution of a copper compound that includes none of sulfur, chlorine and oxygen elements and produces copper ions having a valence of +1 in the solution.

A method of producing a refined copper includes depositing the refined copper on a cathode by an electroplating process or an electroless plating process in an alkaline plating bath including a solution of a copper compound that includes none of sulfur, chlorine and oxygen elements and produces copper ions having a valence of +1 in the solution.

This electrolytic refining method of high-purity electrolytic copper includes: performing electrolysis by using an electrolyte which includes a copper nitrate solution, a cathode made of stainless steel, and an anode made of copper so as to deposit high-purity electrolytic copper on the cathode. (a) The electrolyte includes a mixture of polyethylene glycol and polyvinyl alcohol at a content of 20 ppm or more as an additive. (b) When a molecular weight of the polyethylene glycol is given as Z and a current density during the electrolysis is given as X (A/dm.sup.2), the electrolysis is performed under conditions that fulfill the following relational expressions,
1000≦Z≦2000
1.2−(Z−1000)×0.0008≦X≦2.2−(Z−1000)×0.001.

This electrolytic refining method of high-purity electrolytic copper includes: performing electrolysis by using an electrolyte which includes a copper nitrate solution, a cathode made of stainless steel, and an anode made of copper so as to deposit high-purity electrolytic copper on the cathode. (a) The electrolyte includes a mixture of polyethylene glycol and polyvinyl alcohol at a content of 20 ppm or more as an additive. (b) When a molecular weight of the polyethylene glycol is given as Z and a current density during the electrolysis is given as X (A/dm.sup.2), the electrolysis is performed under conditions that fulfill the following relational expressions,
1000≦Z≦2000
1.2−(Z−1000)×0.0008≦X≦2.2−(Z−1000)×0.001.

The additive for high-purity copper electrolytic refining of the present invention is an additive which is added to a copper electrolyte in electrolytic refining for high-purity copper and is formed of a non-ionic surfactant that includes a hydrophobic group containing an aromatic ring and a hydrophilic group containing a polyoxyalkylene group, in which a dispersion term dD of the Hansen solubility parameters satisfies 10≦dD≦20, a polarity term dP of the Hansen solubility parameters satisfies 6≦dP≦9, and a hydrogen bonding term dH of the Hansen solubility parameters satisfies 9≦dH≦11.

The additive for high-purity copper electrolytic refining of the present invention is an additive which is added to a copper electrolyte in electrolytic refining for high-purity copper and is formed of a non-ionic surfactant that includes a hydrophobic group containing an aromatic ring and a hydrophilic group containing a polyoxyalkylene group, in which a dispersion term dD of the Hansen solubility parameters satisfies 10≦dD≦20, a polarity term dP of the Hansen solubility parameters satisfies 6≦dP≦9, and a hydrogen bonding term dH of the Hansen solubility parameters satisfies 9≦dH≦11.

The additive for high-purity copper electrolytic refining of the present invention is an additive which is added to a copper electrolyte in electrolytic refining for high-purity copper and is formed of a non-ionic surfactant that includes a hydrophobic group containing an aromatic ring and a hydrophilic group containing a polyoxyalkylene group.

The additive for high-purity copper electrolytic refining of the present invention is an additive which is added to a copper electrolyte in electrolytic refining for high-purity copper and is formed of a non-ionic surfactant that includes a hydrophobic group containing an aromatic ring and a hydrophilic group containing a polyoxyalkylene group.

A method is provided for leaching the metals while granulating molten matte, comprising the steps of feeding a molten matte as a falling stream into a granulation chamber, spraying a liquid jet on the stream of molten matte to atomize the matte, and cooling the matte particles thus formed. The liquid jet comprises an acid solution containing water and sulfuric acid so that the acid solution starts leaching metals from the molten matte when the liquid jet contacts the molten matte. Part of product solution from granulation can be circulated to liquid jets to increase the metal content in the solution and to reduce its acid con-tent.