| 摘要 |
PROBLEM TO BE SOLVED: To provide the method for surface-treating an aluminum material by which the generation of gelled aluminum hydroxide is decreased while lowering the load of industrial chemicals on neutralizing a waste liq., the sulfate radical in the gelled aluminum hydroxide is reduced, and the resources are easily utilized. SOLUTION: In the method for surface-treating an aluminum material having an etching stage and an anodization stage, the waste acidic soln. related to the anodization stage is treated by a normal-type reverse-osmosis device, the sulfuric acid concd. liq. and an aged anodization bath after sulfuric acid is recovered are treated by a sulfuric acid-permeable reverse-osmosis device impermeable to aluminum, the concd. liq. is withdrawn outside the system as an aluminum acid sulfate soln. Meanwhile, the permeated liq. from both reverse- osmosis devices and an alkaline soln. related to the etching stage are introduced into a waste liq. neutralizing stage and neutralized, and the generated gelled aluminum hydroxide is recovered.
|
