Reducing aluminosilicate scale in the bayer process

Abstract

The invention provides methods and compositions for inhibiting the accumulation of DSP scale in the liquor circuit of Bayer process equipment. The method includes adding one or more particular silane based small molecules to the liquor fluid circuit. These scale inhibitors reduce DSP scale formation and thereby increase fluid throughput, increase the amount of time Bayer process equipment can be operational and reduce the need for expensive and dangerous acid washes of Bayer process equipment. As a result, the invention provides a significant reduction in the total cost of operating a Bayer process.

1 . A method for reducing aluminosilicate containing scale in a Bayer process comprising: adding to a Bayer liquor an aluminosilicate scale reducing amount of a non-polymeric reaction product resulting from the reaction of:
 a first molecule which is an amine-containing small molecule and   a second molecule which is an amine-reactive molecule containing at least one amine-reactive group per molecule and at least one —Si(OR) n  group per molecule, where n=1, 2, or 3, and R=C 1 -C 12  alkyl, aryl, H, Na, K, Li, or NH 4 .   
     
     
         2 . The method of  claim 1  in which the amine containing molecule is selected from the group consisting of: isophoronediamine, C,C,C-trimethylhexanediamine, hexanediamine, meta-xylenediamine, 4,4′-methylenebiscyclohexylamine, 1,2-diaminocyclohexane, saturated fatty amines, unsaturated fatty amines, N-fatty-1,3-propanediamine, and any combination thereof. 
     
     
         3 . The method of  claim 1  wherein the amine-reactive molecule, is selected from a list comprised of 3-glycidoxypropyltrialkoxysilane, 3-glycidoxypropylalkyldialkoxysilane, 3-glycidoxypropyldialkylmonoalkoxysilane, 3-isocyanatopropyltrialkoxysilane, 3-isocyanatopropylalkyldialkoxysilane, 3-isocyanatopropyldialkylmonoalkoxysilane, 3-chloropropyltrialkoxysilane, 3-chloropropylalkyldialkoxysilane, and 3-chloropropyldialkylmonoalkoxysilane, and any combination thereof. 
     
     
         4 . The method of  claim 1  wherein the reaction product is a product of a reaction between the first molecule with a second molecule and also with a third molecule wherein the third molecule is an amine-reactive hydrophobic molecule with a molecular weight of less than 500 daltons. 
     
     
         5 . The method of  claim 4  in which the amine-reactive hydrophobic small molecule is selected from a group consisting of C 3 -C 22  glycidyl ether, C 3 -C 22  isocyanate, C 3 -C 22  chloride, C 3 -C 22  bromide, C 3 -C 22  iodide, C 3 -C 22  sulfate ester, C 3 -C 22  phenolglycidyl ether, and any combination thereof. 
     
     
         6 . The method of  claim 1  in which the amine containing molecule is selected from the list consisting of cocoalkylpropanediamine, oleylpropanediamine, dodecylpropanediamine, hydrogenized tallowalkylpropanediamine, and tallowalkylpropanediamine. 
     
     
         7 . The method of  claim 1  in which the reaction product comprises molecules having a structure according to that of Formula I: 
       
         
           
           
               
               
           
         
       
     
     
         8 . The method of  claim 1  in which the reaction product comprises molecules having a structure according to that of Formula II: