Method for adding starting material slurry and sulfuric acid to autoclave in high pressure acid leaching process and autoclave

An autoclave in a high pressure acid leaching process in which heated and pressurized starting material slurry and sulfuric acid are stirred by a stirring machine provided in each of compartments in the autoclave partitioned into plurality by partition walls to proceed leaching, and slurry is transferred from a compartment on an upstream side to a compartment on a downstream side to sequentially proceed leaching, wherein

• starting material slurry supply tubes having the starting material slurry discharge ports and sulfuric acid supply tubes having sulfuric acid discharge ports are alternately disposed on a perimeter of stirring blades of the stirring machine provided in a compartment at an upstream end, and the starting material slurry discharge ports and the sulfuric acid discharge ports are positioned at positions higher than an uppermost part of the stirring blades and lower than a contained liquid surface, and
• via the starting material slurry supply tubes and the sulfuric acid supply tubes, the starting material slurry and the sulfuric acid are added to the compartment at the upstream end from the starting material slurry discharge ports and the sulfuric acid discharge ports alternately positioned on the perimeter of the stirring blades and at positions higher than the uppermost part of the stirring blades of the stirring machine and lower than the contained liquid surface.