Process for Removal of Aluminum Oxides from Aqueous Media

Abstract

The present invention relates to the use of lithium salts and/or magnesium salts for the precipitation of aluminum oxides present in aqueous media.

1 . A method for removing soluble aluminum oxides from an aqueous medium comprising contacting a lithium salt with the medium; collecting the resulting precipitated lithium-aluminate complex; and optionally washing the collected lithium-aluminate complex, wherein the aqueous medium contains chemically hazardous or radioactive waste. 
     
     
         2 . The method according to  claim 1 , wherein the lithium salt is selected from the group consisting of Li 2 CO 3 , LiHCO 3 , LiOH, LiNO 2 , LiCl, LiF, Li 3 PO 4 , Li 2 SO 4 , LiNO 3 , LiAc and mixtures thereof. 
     
     
         3 . The method according to  claim 1 , wherein the lithium salt is LiNO 3 . 
     
     
         4 . The method according to  claim 1 , wherein the aluminum oxide is selected from the group consisting of Al 2 O 3 , Al(OH) 3 , AlO(OH) and mixtures thereof. 
     
     
         5 . The method according to  claim 1 , wherein the aluminum oxide is Al(OH) 3 . 
     
     
         6 . The method according to  claim 1 , wherein the aqueous medium further comprises a dissolved inorganic salt selected from the group consisting of NaNO 3 , NaNO 2 , Na 2 CO 3 , Na 2 SO 4 , NaF, Na 3 PO 4 , NaOH, KOH, Na 2 CrO 4  and mixtures thereof. 
     
     
         7 . The method according to  claim 1 , wherein the lithium-aluminate complex is LAHCS. 
     
     
         8 . The method according to  claim 1 , wherein the temperature of the aqueous medium during the contacting step is at least about 50° C. to about 100° C. 
     
     
         9 . The method according to  claim 1 , further comprising contacting the aqueous medium with a magnesium salt to cause precipitation of a magnesium-aluminate complex. 
     
     
         10 . A method for removing soluble aluminum oxides from an aqueous medium comprising contacting a magnesium salt with the medium; collecting the resulting precipitated magnesium-aluminate complex; and optionally washing the collected magnesium-aluminate complex, wherein the aqueous medium contains chemically hazardous or radioactive waste. 
     
     
         11 . The method according to  claim 10 , wherein the magnesium salt is selected from the group consisting of MgCO 3 , Mg(HCO 3 ) 2 , Mg(OH) 2 , Mg(NO 2 ) 2 , MgCl 2 , MgF 2 , Mg 3 (PO 4 )I, MgSO 4 , Mg(NO 3 ) 2 , MgAc and mixtures thereof. 
     
     
         12 . The method according to  claim 10 , wherein the magnesium salt is Mg(NO 2 ) 2 . 
     
     
         13 . The method according to  claim 10 , wherein the aluminum oxide is selected from the group consisting of Al 2 O 3 , Al(OH) 3 , AlO(OH) and mixtures thereof. 
     
     
         14 . The method according to  claim 10 , wherein the aluminum oxide is Al(OH) 3 . 
     
     
         15 . The method according to  claim 10 , wherein the aluminum oxide is an aluminosilicate. 
     
     
         16 . The method according to  claim 10 , wherein the aqueous medium further comprises a dissolved inorganic salt selected from the group consisting of NaNO 3 , NaNO 2 , Na 2 CO 3 , Na 2 SO 4 , NaF, Na 3 PO 4 , NaOH, KOH, Na 2 CrO 4  and mixtures thereof. 
     
     
         17 . The method according to  claim 10 , wherein the magnesium-aluminate complex is a hydrotalcite. 
     
     
         18 . The method according to  claim 10 , wherein the temperature of the aqueous medium during the contacting step is at least about 50° C. to about 100° C. 
     
     
         19 . The method according to  claim 10 , further comprising contacting the aqueous medium with a lithium salt to cause precipitation of a lithium-aluminate complex.