Method of adding raw slurry and sulfuric acid to autoclave in high pressure acid leaching process and autoclave

摘要

In an autoclave 100 in a high pressure acid leaching process in which heated and pressurized starting material slurry and sulfuric acid are stirred by stirring machines 30A, 30B ... provided in each of compartments 20A, 20B ... in the autoclave partitioned into plurality by partition walls 10A, 10B ... 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 41 and 42 having the starting material slurry discharge ports 41A and 42A alternately disposed and sulfuric acid supply tubes 51 and 52 having sulfuric acid discharge ports 51A and 52A are alternately disposed on a perimeter of stirring blades 31A of the stirring machine 30A provided in the compartment 20A at an upstream end, and the starting material slurry and sulfuric acid are added to the compartment 20A at the upstream end from the starting material slurry discharge ports 41A and 42A and the sulfuric acid discharge ports 51A and 52A positioned at positions higher than an uppermost part of the stirring blades 31A and lower than a contained liquid surface L. With this, mixing of the starting material slurry and sulfuric acid is promoted, and control values of concentrations of free sulfuric acid after discharge are reduced.