Pickling method and pickling system of steel sheet

Abstract

The present invention provides a pickling method of steel sheet and pickling system of steel sheet able to efficiently remove oxide scale from steel sheet. That is, it provides a continuous pickling method of steel sheet having a step A of pickling the steel sheet in a pickling tank, a step B of blowing gas toward at least part of the surfaces of the steel sheet in the air after the step A, and a step C of pickling the steel sheet in a pickling tank after the step B, wherein at step B, the steel sheet is temporarily taken out from the pickling solution and gas is blown to at least part of the surfaces of the steel sheet in the air so as to evaporate the acid solution deposited on the surface of the steel sheet and locally increase the acid concentration to thereby efficiently remove even the stubborn Si oxides included in the oxide scale.

1 . A pickling method of steel sheet comprising a pickling method for removing oxide scale of steel sheet characterized by having a step A of pickling the steel sheet, a step B of blowing gas toward at least part of the surfaces of the steel sheet in the air after said step A, and a step C of pickling said steel sheet after said step B. 
     
     
         2 . A continuous pickling method of steel sheet as set forth in  claim 1 , characterized by blowing said gas against a direction of movement of the steel sheet. 
     
     
         3 . A pickling method of steel sheet as set forth in  claim 2 , characterized in that an angle θ (°) formed between a blowing direction of said gas and at least part of the surfaces of the steel sheet is 1°≦θ≦75°. 
     
     
         4 . A pickling method of steel sheet as set forth in  claim 1 , characterized in that a blowing pressure of said gas is 0.5 to 1.0 MPa. 
     
     
         5 . A pickling method of steel sheet as set forth in  claim 1 , characterized in the pickling of said step A is performed in a first pickling tank and the pickling of said step C is performed in a second pickling tank. 
     
     
         6 . A pickling system of steel sheet characterized by having at least one pickling tank and means for blowing gas toward at least part of the surfaces of the steel sheet in the air. 
     
     
         7 . A continuous pickling system of steel sheet as set forth in  claim 6 , characterized in that said means for blowing gas is a means for blowing it facing the direction of movement of the steel sheet. 
     
     
         8 . A pickling system of steel sheet as set forth in  claim 6 , characterized in that an angle θ (°) formed between a blowing direction of said gas and at least part of the surfaces of the steel sheet is 1°≦θ≦75°. 
     
     
         9 . A pickling system of steel sheet as set forth in  claim 6 , characterized in that said means for blowing gas is a nozzle. 
     
     
         10 . A pickling system of steel sheet as set forth in  claim 9 , characterized in that said nozzle has an angle changing means. 
     
     
         11 . A pickling system of steel sheet as set forth in  claim 9 , characterized in that a pressure at a blowing port of said nozzle is 0.5 to 1.0 MPa. 
     
     
         12 . A pickling system of steel sheet as set forth in  claim 9 , characterized two or more of said nozzles are arranged in the direction of movement of the steel sheet. 
     
     
         13 . A pickling system of steel sheet as set forth in  claim 6 , characterized in that said piddling tank is two or more pickling tanks.