Filter aid and method of using same for reclaiming water-based fluids used in metal working processes

Abstract

A filter aid and a method of using the same are disclosed that effectively removes contaminants from water-based metal forming liquids used in aluminum forming, rolling and other metal working processes. The filter aid includes a cellulosic material and a cationic polymer flocculating agent that is mixed with contaminated metal working fluid for a predetermined amount of time. The contaminated metal working fluid is then filtered through the filter aid, thereby removing the substantially all of the contaminants therein and allowing purified metal working fluid to return to the process system without carrying contaminants that will harm the surfaces of the metal being worked and the device that forms them. An acid material may be optionally added to the metal forming liquid, the acid serving to maintain the pressure and flow rate at normal levels by controlling clogging in the filter.

1 . A filter aid for use in a filtering system for removing metal particles, tramp oil, and other contaminants from an oil-in-water emulsion produced in a metal working process, the filter aid comprised of: 
 a cellulosic material; and    an cationic polymer flocculating agent.    
     
     
         2 . The filter aid set forth in  claim 1 , wherein the cellulosic material is a powdered cellulose fiber.  
     
     
         3 . The filter aid set forth in  claim 1 , wherein the cationic polymer flocculating agent is a cationic amine or imine salt polymer.  
     
     
         4 . The filter aid set forth in  claim 3 , wherein the cationic amine or imine salt polymer is one selected from a group consisting of poly[oxyethylene(dimethylimino)ethylene(dimethylinino)ethylene dichloride, polydimethyliallyl ammonium chloride, and tetraalkyl quaternary ammonium chloride.  
     
     
         5 . The filter aid set forth in  claim 1 , wherein the ratio of cellulosic material to cationic polymer flocculating agent in the filter aid is between approximately 5:1 and 30:1.  
     
     
         6 . A method for removing metal particles, tramp oil, and other contaminants from an oil-in-water emulsion produced in a metal working process, the method comprising the steps of: 
 supplying a filter aid comprised of a cellulosic material and a cationic polymer flocculating agent to the oil-in-water emulsion;    allowing the filter aid to react with the oil-in-water emulsion for a predetermined amount of time in order to form a floc therein;    passing a flow of the oil-in-water emulsion through the filter aid and a filter sheet in order to filter the floc and other contaminants from the oil-in-water emulsion; and    collecting filtered oil-in-water emulsion from the filter aid.    
     
     
         7 . The method set forth in  claim 6 , further comprising the step of supplying an acid material to the mixture of the oil-in-water emulsion and the filter aid after a predetermined pressure drop is detected across the filter sheet.  
     
     
         8 . The method set forth in  claim 7 , wherein the acid material is one selected from the group consisting of sulfuric acid, salicylic acid, fumaric acid, and citric acid.  
     
     
         9 . The method set forth in  claim 7 , wherein the acid material is approximately 0.1 wt % citric acid.  
     
     
         10 . The method set forth in  claim 6 , wherein the cellulosic material is a powdered cellulose fiber, and the cationic polymer flocculating agent is a cationic amine or imine salt polymer.  
     
     
         11 . The method set forth in  claim 6 , wherein the ratio of cellulosic material to cationic polymer flocculating agent in the filter aid is between approximately 5:1 and 30:1.  
     
     
         12 . The method set forth in  claim 6 , wherein the predetermined amount of time is between approximately 1 and 15 minutes.  
     
     
         13 . The method set forth in  claim 7 , further comprising the step of supplying dilute sodium hydroxide solution to the filter aid formed on the filter sheet after the acid material supplying step.