Sulfate salt desalination for gold sulfite plating solution

Abstract

Sulfate salts are removed from a gold sulfite plating solution via supersaturating a sulfate-rich gold sulfite plating solution to form a sulfate-poor saturated gold sulfite plating solution, and un-saturating the sulfate-poor saturated gold sulfite plating solution to form an unsaturated sulfate-poor gold sulfite plating solution. Gold from the unsaturated sulfate-poor gold sulfite plating solution is electrodeposited onto a workpiece.

What is claimed is: 
     
         1 . A method for removing sulfate salts from a gold sulfite plating solution, comprising:
 supersaturating a sulfate-rich gold sulfite plating solution to form a supersaturated sulfate-rich gold sulfite plating solution;   exposing the supersaturated sulfate-rich gold sulfite plating solution to a nucleator to form sulfate salts and a sulfate-poor saturated gold sulfite plating solution; and   un-saturating the sulfate-poor saturated gold sulfite plating solution to form an unsaturated sulfate-poor gold sulfite plating solution.   
     
     
         2 . The method of  claim 1  further comprising electrodepositing gold from the unsaturated sulfate-poor gold sulfite plating solution onto a workpiece. 
     
     
         3 . The method of  claim 1 , wherein the supersaturating includes cooling the sulfate-rich gold sulfite plating solution. 
     
     
         4 . The method of  claim 1 , wherein the supersaturating includes concentrating the sulfate-rich gold sulfite plating solution. 
     
     
         5 . The method of  claim 4 , wherein the concentrating includes evaporating. 
     
     
         6 . The method of  claim 4 , wherein the concentrating includes filtering. 
     
     
         7 . The method of  claim 6 , wherein the filtering is via reverse osmosis. 
     
     
         8 . The method of  claim 1 , wherein the un-saturating includes heating the sulfate-poor saturated gold sulfite plating solution. 
     
     
         9 . The method of  claim 1 , wherein the un-saturating includes hydrating the sulfate-poor saturated gold sulfite plating solution. 
     
     
         10 . The method of  claim 1 , wherein the nucleator is crystalized sulfate salt or crystalline structure nucleation sites. 
     
     
         11 . A method for removing sulfate salts from a gold sulfite plating solution, comprising:
 supersaturating a sulfate-rich gold sulfite plating solution in a presence of a sulfate nucleator to form sulfate salt precipitate and a sulfate-poor saturated gold sulfite plating solution; and   un-saturating the sulfate-poor saturated gold sulfite plating solution to form an unsaturated sulfate-poor gold sulfite plating solution.   
     
     
         12 . The method of  claim 11  further comprising electrodepositing gold from the unsaturated sulfate-poor gold sulfite plating solution onto a workpiece. 
     
     
         13 . The method of  claim 11 , wherein the supersaturating includes cooling the sulfate-rich gold sulfite plating solution. 
     
     
         14 . The method of  claim 11 , wherein the supersaturating includes concentrating the sulfate-rich gold sulfite plating solution. 
     
     
         15 . The method of  claim 14 , wherein the concentrating includes evaporating. 
     
     
         16 . The method of  claim 14 , wherein the concentrating includes filtering. 
     
     
         17 . The method of  claim 16 , wherein the filtering is via reverse osmosis. 
     
     
         18 . The method of  claim 11 , wherein the un-saturating includes heating the sulfate-poor saturated gold sulfite plating solution. 
     
     
         19 . The method of  claim 11 , wherein the un-saturating includes hydrating the sulfate-poor saturated gold sulfite plating solution. 
     
     
         20 . The method of  claim 11 , wherein the sulfate nucleator is crystalized sulfate salt or crystalline structure nucleation sites.