Tin stripping additive and application thereof

Abstract

The present invention provides an additive for tin stripping, comprising 0.1 to 20 wt % of copper corrosion inhibitor and 0.1 to 20 wt % of nickel corrosion inhibitor; wherein said weight percentage is based on the total weight of said additive. The present additive can be used with nitric acid conventionally used for metal-stripping for not only reducing the usage of nitric acid but also improving the efficiency of tin stripping. The present invention also provides a method for Tin recycle and a reaction tank for metal recycle. Both of them are favorable for satisfying the needs of metal recycle (especially, tin recycle) in the field.

What is claimed is: 
     
         1 . A tin stripping additive, comprising:
 0.1 to 20 wt % of copper corrosion inhibitor; and   0.1 to 20 wt % of nickel corrosion inhibitor;   wherein, remaining wt % of said tin stripping additive is a solvent;   wherein, said wt % is based on the total weight of said tin stripping additive.   
     
     
         2 . The tin stripping additive of  claim 1 , wherein said copper corrosion inhibitor is a phosphate salt. 
     
     
         3 . The tin stripping additive of  claim 2 , wherein said phosphate salt is potassium phosphate, potassium dihydrogen phosphate, dipotassium phosphate, trisodium phosphate, or a combination thereof. 
     
     
         4 . The Tin stripping additive of  claim 1 , wherein said nickel corrosion inhibitor is sodium oxalate, ammonium chloride, potassium carbonate, sodium metanitrobenzene sulfonate, or a combination thereof. 
     
     
         5 . A tin stripping solution, comprising:
 20 to 50%(v/v) of the Tin stripping additive of  claim 1 ; and   20 to 50%(v/v) of nitric acid; wherein said %(v/v) is based on the total volume of said tin stripping solution.   
     
     
         6 . The tin stripping solution of  claim 5 , wherein said nitric acid is of a concentration of 67 to 68 wt %. 
     
     
         7 . The tin stripping solution of  claim 5 , further comprising a solvent. 
     
     
         8 . The tin stripping solution of  claim 7 , wherein said solvent is water. 
     
     
         9 . A method for tin-recycling, comprising the following steps:
 (A) immersing an object to be processed into the tin stripping solution of  claim 5  to obtain a wash-off solution;   (B) adding an alkaline solution to said wash-off solution to obtain a precipitate;   (C) heating said precipitate; and   (D) conducting a reduction reaction to said precipitate being heated in said step (C) to obtain tin.   
     
     
         10 . The method of  claim 9 , wherein said immersing is achieved by placing said object to be processed into a bath of said tin stripping solution. 
     
     
         11 . The method of  claim 10 , wherein said bath is of a temperature of 20 to 60° C. 
     
     
         12 . The method of  claim 9 , wherein said alkaline solution is sodium hydroxide, potassium hydroxide, or a combination thereof. 
     
     
         13 . The method of  claim 9 , wherein said heating of said step (C) is conducted at a temperature of 600 to 800° C. 
     
     
         14 . The method of  claim 9 , wherein said reduction reaction is conducted by heating said precipitate of step (C) in a gas mixture atmosphere of hydrogen and nitrogen. 
     
     
         15 . The method of  claim 14 , wherein said gas mixture comprises:
 20 to 30%(v/v) of hydrogen; and   70 to 80%(v/v) of nitrogen;   wherein said %(v/v) is based on the total volume of said gas mixture.   
     
     
         16 . A reaction tank, comprising:
 a body, comprising an inlet, an outlet, a sidewall, and a gas inlet; wherein said sidewall defines an inner space; wherein an area of said inner space adjacent to said outlet is a collection area;   a first heating apparatus, positioned to surround at least parts of said sidewall; and   a sieve, positioned inside said inner space to separate said inner space into two spaces.