Molten-salt composition for anodic sulfuring of the surfaces of iron and steel and the process and plant for anodic sulf uring

摘要

There are provided a molten composition used for the formation of sulfide conversion film on surfaces of iron and steel by means of electrolysis, a process specially used for the said anodic sulfuring, and an equipment specially used for the said anodic sulfuring process. The molten salts composition was prepared by using of potassium thiocyanate, sodium thiocyanate, iron oxides, sulfide, conductive salt and sulfate or chloride of mixed rear earth. The said process includes the steps of concentrating and recovery of valuable ingredients in the washing liquid for treated workpieces so as to prepare recovered salts and in the latter addition step, to mix the recovered salts with fresh salts, and to pretreat the resulting salts mixture, when supplementing the said salt mixture, the addition quantity is controlled in accordance with both of the quantity of the drug-out by the treated workpieces and the quantity of the newly added molten salt needed by the workpieces to be treated, so as to maintain the dynamic balances between the chemical condition and electrochemical condition for anodic sulfuring. The plant for anodic sulfuring provided by the present invention laid the base for automatic large-scale production of anodic sulfuring.