Agglomeration of alumina and binder therefor

Abstract

A method for the agglomeration of alumina particles, the method comprising the steps of comminuting a plurality of alumina particles having a soda content of less than approximately 0.4% by weight to a D 50 of less than 12μ, adding a quantity of pseudo-boehmite as an aqueous suspension having a pH of from about 2 to 6 to the plurality of alumina particles to form a mixture such that the quantity of pseudo-boehmite is between about 0.8 wt % and 5 wt % based on weight of the mixture, and spray drying the mixture to produce agglomerated granules.

1 . Agglomerated granules containing alumina, the agglomerated granules being produced by:
 comminuting a plurality of alumina particles having a soda content of less than approximately 0.4% by weight to a D 50  of less than 12 μm;   adding a quantity of pseudo-boehmite as an aqueous suspension having a pH of from about 2 to 6 to said plurality of alumina particles to form a mixture such that the quantity of pseudo-boehmite is between about 0.8 wt % and 5 wt % based on weight of said mixture; and   spray drying said mixture.   
   
   
       2 . The agglomerated granules produced according to  claim 1 , further comprising forming the pseudo-boehmite suspension at a temperature between about 15 and 100° C. 
   
   
       3 . The agglomerated granules produced according to  claim 1 , further comprising forming the pseudo-boehmite suspension at a temperature above about 80° C. 
   
   
       4 . The agglomerated granules produced according to  claim 1 , further comprising forming the pseudo-boehmite suspension at a temperature above about 85° C. 
   
   
       5 . The agglomerated granules produced according to  claim 1 , wherein the pH of said pseudo-boehmite suspension is approximately 3. 
   
   
       6 . The agglomerated granules produced according to  claim 1 , further comprising adding a quantity of monoprotic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6. 
   
   
       7 . The agglomerated granules produced according to  claim 1 , further comprising adding a quantity of acetic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6. 
   
   
       8 . The agglomerated granules produced according to  claim 1 , wherein before adding the quantity of said pseudo-boehmite to said alumina particles, the alumina particles are comminuted to a D 50  of less than about 9 μm. 
   
   
       9 . The agglomerated granules produced according to  claim 1 , wherein before adding a quantity of said pseudo-boehmite to said alumina particles, the alumina particles are comminuted to a D 50  of less than about 5 μm. 
   
   
       10 . The agglomerated granules produced according to  claim 1 , wherein before adding the quantity of pseudo-boehmite to said alumina particles, the alumina particles are neutralized, dewatered, and washed. 
   
   
       11 . The agglomerated granules produced according to  claim 10 , further comprising using carbon dioxide to neutralize said alumina particles. 
   
   
       12 . The agglomerated granules produced according to  claim 10 , wherein neutralizing, dewatering, and washing said alumina particles are carried out before grinding said alumina particles. 
   
   
       13 . The agglomerated granules produced according to  claim 1 , further comprising heating said agglomerated granules. 
   
   
       14 . The agglomerated granules produced according to  claim 13 , further comprising dehydroxylating the agglomerated particles by heating the agglomerated particles to approximately 300° C. 
   
   
       15 . The agglomerated granules produced according to  claim 13 , further comprising calcining the agglomerated granules above 500° C. 
   
   
       16 . The agglomerated granules produced according to  claim 1 , wherein the agglomerated granules have a D 50  in the range of about 150 to 300 μm. 
   
   
       17 . The agglomerated granules produced according to  claim 1 , wherein said plurality of alumina particles has a soda content of less than approximately 0.35% by weight. 
   
   
       18 . The agglomerated granules produced according to  claim 1 , wherein said plurality of alumina particles has a soda content of less than approximately 0.30% by weight. 
   
   
       19 . The agglomerated granules produced according to  claim 1 , wherein said plurality of alumina particles has a soda content of less than approximately 0.25% by weight. 
   
   
       20 . Agglomerated granules containing alumina, the agglomerated granules being produced by:
 adding a quantity of water to a plurality of alumina particles having a soda content of less than approximately 0.4% by weight to form a slurry;   grinding said alumina particles in said slurry to a D 50  of less than 12 μm;   adding a quantity of pseudo-boehmite as an aqueous suspension having a pH of from about 2 to 6 to said slurry to form a mixture such that the quantity of said pseudo-boehmite is between about 0.8 wt % and 5 wt % based on weight of said mixture; adding a viscosity modifier to said slurry, said mixture or said aqueous suspension such that the viscosity of said mixture is less than about 4 cp; and   spray drying said mixture.   
   
   
       21 . The agglomerated granules produced according to  claim 20 , wherein said viscosity modifier is acetic acid and the concentration of said acetic acid in said slurry is between about 0.2 and 1.5% by weight of said alumina particles. 
   
   
       22 . The agglomerated granules produced according to  claim 20 , wherein said plurality of alumina particles has a soda content of less than approximately 0.35% by weight. 
   
   
       23 . The agglomerated granules produced according to  claim 20 , wherein said plurality of alumina particles has a soda content of less than approximately 0.30% by weight. 
   
   
       24 . The agglomerated granules produced according to  claim 20 , wherein said plurality of alumina particles has a soda content of less than approximately 0.25% by weight. 
   
   
       25 . The agglomerated granules produced according to  claim 20 , wherein said viscosity modifier contains one or more acetic acid, citric acid, or a polyacrylate. 
   
   
       26 . The agglomerated granules produced according to  claim 20 , wherein said slurry is of a high density. 
   
   
       27 . The agglomerated granules produced according to  claim 20 , wherein in said slurry comprises at least about 50% solids. 
   
   
       28 . The agglomerated granules produced according to  claim 20 , wherein said slurry comprises between about 40 and 60% solids. 
   
   
       29 . The agglomerated granules produced according to  claim 20 , further comprising forming the pseudo-boehmite suspension at a temperature between about 15 and 100° C. 
   
   
       30 . The agglomerated granules produced according to  claim 20 , further comprising forming the pseudo-boehmite suspension at a temperature above about 80° C. 
   
   
       31 . The agglomerated granules produced according to  claim 20 , further comprising forming the pseudo-boehmite suspension at a temperature above about 85° C. 
   
   
       32 . The agglomerated granules produced according to  claim 20 , wherein the pH of said pseudo-boehmite suspension is approximately 3. 
   
   
       33 . The agglomerated granules produced according to  claim 20 , further comprising adding a quantity of monoprotic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6. 
   
   
       34 . The agglomerated granules produced according to  claim 20 , further comprising adding a quantity of acetic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6. 
   
   
       35 . The agglomerated granules produced according to  claim 34 , wherein adding the quantity of acetic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6 and adding the viscosity modifier to said slurry, said mixture, or said aqueous suspension such that the viscosity of said mixture is less than about 4 cp are performed concurrently by the addition of a single quantity of acetic acid to said aqueous suspension. 
   
   
       36 . The agglomerated granules produced according to  claim 20 , wherein before adding the quantity of said pseudo-boehmite to said alumina particles, the alumina particles are comminuted to a D 50  of less than about 9 μm. 
   
   
       37 . The agglomerated granules produced according to  claim 20 , wherein before adding a quantity of said pseudo-boehmite to said alumina particles, the alumina particles are comminuted to a D 50  of less than about 5 μm. 
   
   
       38 . The agglomerated granules produced according to  claim 20 , wherein before adding the quantity of said pseudo-boehmite to said alumina particles, the alumina particles are neutralized, dewatered, and washed. 
   
   
       39 . The agglomerated granules produced according to  claim 38 , wherein dewatering is achieved by way of filtration. 
   
   
       40 . The agglomerated granules produced according to  claim 38 , wherein dewatering is achieved by way of centrifugation. 
   
   
       41 . The agglomerated granules produced according to  claim 38 , further comprising using carbon dioxide to neutralize said alumina particles. 
   
   
       42 . The agglomerated granules produced according to  38 , wherein neutralizing, dewatering, and washing said alumina particles is carried out before grinding said alumina particles. 
   
   
       43 . The agglomerated granules produced according to  claim 20 , further comprising heating said agglomerated granules. 
   
   
       44 . The agglomerated granules produced according to  claim 43 , further comprising dehydroxylating the agglomerated particles by heating the agglomerated particles to approximately 300° C. 
   
   
       45 . The agglomerated granules produced according to  claim 43 , further comprising calcining the agglomerated granules above 500° C. 
   
   
       46 . The agglomerated granules produced according to  claim 20 , wherein the agglomerated granules have a D 50  in the range of about 150 to 300 μm. 
   
   
       47 . Agglomerated granules containing alumina, the agglomerated granules being produced by:
 grinding a plurality of alumina particles having a soda content of less than approximately 0.4% by weight to a D 50  of less than 12 μm;   adding a quantity of water to said alumina particles to form a slurry;   adding a quantity of pseudo-boehmite as an aqueous suspension having a pH of from about 2 to 6 to said slurry to form a mixture such that the quantity of said pseudo-boehmite is between about 0.8 wt % and 5 wt % based on weight of said mixture;   adding a viscosity modifier to said slurry, said mixture or said aqueous suspension such that the viscosity of said mixture is less than about 4 cp; and   spray drying said mixture.   
   
   
       48 . The agglomerated granules produced according to  claim 47 , wherein said viscosity modifier is acetic acid and the concentration of said acetic acid in said slurry is between about 0.2 and 1.5% by weight of said alumina particles. 
   
   
       49 . The agglomerated granules produced according to  claim 47 , wherein said plurality of alumina particles has a soda content of less than approximately 0.35% by weight. 
   
   
       50 . The agglomerated granules produced according to  claim 47 , wherein said plurality of alumina particles has a soda content of less than approximately 0.30% by weight. 
   
   
       51 . The agglomerated granules produced according to  claim 47 , wherein said plurality of alumina particles has a soda content of less than approximately 0.25% by weight. 
   
   
       52 . The agglomerated granules produced according to  claim 47 , wherein said viscosity modifier contains one or more acetic acid, citric acid, or a polyacrylate. 
   
   
       53 . The agglomerated granules produced according to  claim 47 , wherein said slurry is of a high density. 
   
   
       54 . The agglomerated granules produced according to  claim 47 , wherein said slurry comprises at least about 50% solids. 
   
   
       55 . The agglomerated granules produced according to  claim 47 , wherein said slurry comprises between about 40 and 60% solids. 
   
   
       56 . The agglomerated granules produced according to  claim 47 , further comprising forming the pseudo-boehmite suspension at a temperature between about 15 and 100° C. 
   
   
       57 . The agglomerated granules produced according to  claim 47 , further comprising forming the pseudo-boehmite suspension at a temperature above about 80° C. 
   
   
       58 . The agglomerated granules produced according to  claim 47 , further comprising forming the pseudo-boehmite suspension at a temperature above about 85° C. 
   
   
       59 . The agglomerated granules produced according to  claim 47 , wherein the pH of said pseudo-boehmite suspension is approximately 3. 
   
   
       60 . The agglomerated granules produced according to  claim 47 , further comprising adding a quantity of monoprotic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6. 
   
   
       61 . The agglomerated granules produced according to  claim 47 , further comprising adding a quantity of acetic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6. 
   
   
       62 . The agglomerated granules produced according to  claim 61 , wherein adding the quantity of acetic acid to said pseudo-boehmite suspension such that the pH of said pseudo-boehmite suspension is between about 2 and 6 and adding the viscosity modifier to said slurry, said mixture, or said aqueous suspension such that the viscosity of said mixture is less than about 4 cp are performed concurrently by the addition of a single quantity of acetic acid to said aqueous suspension. 
   
   
       63 . The agglomerated granules produced according to  claim 47 , wherein before adding the quantity of said pseudo-boehmite to said alumina particles, the alumina particles are comminuted to a D 50  of less than about 9 μm. 
   
   
       64 . The agglomerated granules produced according to  claim 47 , wherein before adding the quantity of said pseudo-boehmite to said alumina particles, the alumina particles are comminuted to a D 50  of less than about 5 μm. 
   
   
       65 . The agglomerated granules produced according to  claim 47 , wherein before adding the quantity of said pseudo-boehmite to said alumina particles, the alumina particles are neutralized, dewatered, and washed. 
   
   
       66 . The agglomerated granules produced according to  claim 65 , further comprising using carbon dioxide to neutralize said alumina particles. 
   
   
       67 . The agglomerated granules produced according to  claim 65 , wherein neutralizing, dewatering, and washing said alumina particles are carried out before grinding said alumina particles. 
   
   
       68 . The agglomerated granules produced according to  claim 47 , further comprising heating said agglomerated granules. 
   
   
       69 . The agglomerated granules produced according to  claim 68 , further comprising dehydroxylating the agglomerated particles by heating the agglomerated particles to approximately 300° C. 
   
   
       70 . The agglomerated granules produced according to  claim 68 , further comprising calcining the agglomerated granules above 500° C. 
   
   
       71 . The agglomerated granules produced according to  claim 47 , wherein said agglomerated granules have a D 50  in the range of about 150 to 300 μm. 
   
   
       72 . The agglomerated granules produced according to  claim 47 , wherein said quantity of water is provided in the form of said aqueous suspension.