Polymers for preventing or reducing aluminosilicate scale in a bayer process

Abstract

Materials and a process are provided whereby polymers with the pendant group or end group containing —Si(OR″) 3 (where R″ is H, an alkyl group, Na, K, or NH 4 ) are used to control aluminosilicate scaling in a Bayer process. When materials of the present invention are added to the Bayer liquor before the heat exchangers, they reduce and even completely prevent formation of aluminosilicate scale on heat exchanger walls. The present materials are effective at treatment concentrations that make them economically practical.

1 . A polymer for use in the reduction of aluminosilicate containing scale according to the formula: 
     
       
         
         
             
             
         
       
     
     where:
 x=1-99%, y=1-99%, z=0.5-20% and
 M=Na, K, NH 4 ; and 
 R″═H, C1-C3 alkyl, aryl, Na, K or NH 4 . 
 
 
   
   
       2 . The polymer in accordance with  claim 1  according to the formula: 
     
       
         
         
             
             
         
       
     
     where:
 x=1-99%, y=1-99%, z=0.5-20%. 
 
   
   
       3 . A polymer for use in the reduction of aluminosilicate containing scale, wherein the polymer is a graft copolymer of Formula a or Formula b: 
     
       
         
         
             
             
         
       
     
     where
 x=0.1-99% (as percentage of monomer units in the polymer) and
 X═NH, NR′ or O; 
 R′═C1-C10 alkyl, or aryl and 
 R″═H, C1-C3 alkyl, aryl, Na, K or NH 4 .