Stabilized Kaolin Slurry and Methods for Improving Kaolin Slurry Stability

Abstract

Disclosed herein are stabilized kaolin slurries comprising a kaolin comprising no more than about 80% by weight of particles having an equivalent spherical diameter of less than 2 microns and at least one stabilizer, wherein the stabilized kaolin slurry has a 28-day pour test result of at least about 80% poured. Also disclosed are methods of making such stabilized kaolin slurries.

1 . A stabilized kaolin slurry comprising: a kaolin comprising no more than about 80% by weight of particles having an equivalent spherical diameter (ESD) of less than 2 microns; wherein said stabilized kaolin slurry has a solids content of at least about 40%, and a 28-day pour test result of at least about 80% poured.  
   
   
       2 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized kaolin slurry has a pH ranging from about 4.5 to about 7.5.  
   
   
       3 - 6 . (canceled)  
   
   
       7 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized kaolin slurry is substantially free of a dispersant.  
   
   
       8 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized kaolin slurry comprises at least one dispersant.  
   
   
       9 . (canceled)  
   
   
       10 . The stabilized kaolin slurry according to  claim 8 , wherein the at least one dispersant is present in an amount ranging from about 100 ppm to about 500 ppm on a dry basis relative to the total weight of the slurry.  
   
   
       11 . The stabilized kaolin slurry according to  claim 8 , wherein said at least one dispersant is chosen from polyacrylates, polyphosphates, and silicates.  
   
   
       12 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized kaolin slurry has a 28-day pour test result of at least about 85% poured.  
   
   
       13 . The stabilized kaolin slurry according to  claim 12 , wherein said stabilized kaolin slurry has a 28-day pour test result of at least about 89% poured.  
   
   
       14 . The stabilized kaolin slurry according to  claim 1 , wherein said kaolin comprises no more than about 70% by weight of particles having an ESD of less than 2 microns.  
   
   
       15 . The stabilized kaolin slurry according to  claim 14 , wherein said kaolin comprises no more than about 60% by weight of particles having an ESD of less than 2 microns.  
   
   
       16 . The stabilized kaolin slurry according to  claim 15 , wherein said kaolin comprises no more than about 50% by weight of particles having an ESD of less than 2 microns.  
   
   
       17 . The stabilized kaolin slurry according to  claim 16 , wherein said kaolin comprises no more than about 40% by weight of particles having an ESD of less than 2 microns.  
   
   
       18 - 19 . (canceled)  
   
   
       20 . The stabilized kaolin slurry according to  claim 14 , wherein said kaolin comprises from about 25% to about 45% by weight of particles having an ESD of less than 2 microns.  
   
   
       21 . The stabilized kaolin slurry according to  claim 20 , wherein said kaolin comprises about 35% weight of particles having an ESD of less than 2 microns.  
   
   
       22 . The stabilized kaolin slurry according to  claim 1 , wherein said kaolin has a shape factor of at least about 25.  
   
   
       23 - 24 . (canceled)  
   
   
       25 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized kaolin slurry has a solids content ranging from about 45% to about 60%.  
   
   
       26 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized kaolin slurry has a Brookfield viscosity at 50% adjusted solids ranging from about 300 cps to about 700 cps using a #2 spindle at 20 rpm.  
   
   
       27 . (canceled)  
   
   
       28 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized kaolin slurry has a Hercules viscosity at 50% adjusted solids of less than 10 dynes at 4400 rpm using an “A” bob.  
   
   
       29 . The stabilized kaolin slurry according to  claim 1 , wherein said stabilized slurry has a conductivity of no more than about 100 μS.  
   
   
       30 . The stabilized kaolin slurry according to  claim 29 , wherein said stabilized slurry has a conductivity of no more than about 80 μS.  
   
   
       31 . (canceled)  
   
   
       32 . The stabilized kaolin slurry according to  claim 1 , further comprising at least one stabilizer.  
   
   
       33 . The stabilized kaolin slurry according to  claim 32 , wherein said stabilized slurry has a pH ranging from about 5.5 to about 9.5.  
   
   
       34 . (canceled)  
   
   
       35 . The stabilized kaolin slurry according to  claim 32 , wherein said at least one stabilizer comprises at least one cellulosic thickener.  
   
   
       36 . The stabilized kaolin slurry according to  claim 35 , wherein said at least one cellulosic thickener comprises carboxymethylcellulose.  
   
   
       37 . The stabilized kaolin slurry according to  claim 35 , wherein said at least one cellulosic thickener is chosen from alkyl celluloses, ethyl hydroxyethyl celluloses, hydroxymethyl celluloses, hydroxyethyl celluloses, and hydroxypropyl celluloses.  
   
   
       38 . The stabilized kaolin slurry according to  claim 32 , wherein said at least one stabilizer is chosen from montmorillonite, smectite clays, hydrophobically modified ethoxylated urethanes, polyacrylates, polyvinyl pyrrolidone, sodium alginate, xanthan gum, silica thickeners, sodium magnesium silicate, acrylic acid copolymers, and nonionic hydrophobically modified polyethers.  
   
   
       39 . The stabilized kaolin slurry according to  claim 32 , wherein said at least one stabilizer is present in an amount ranging from about 0.01% to about 4% by weight, relative to the total weight of the slurry.  
   
   
       40 . (canceled)  
   
   
       41 . A method of making a stabilized kaolin slurry, comprising: filtering and rinsing a kaolin slurry to remove salt residue therefrom until said resulting kaolin has a conductivity of no more than about 100 μS; resolubilizing said resulting kaolin to form a resolubilized slurry; and adding at least one stabilizer to the resolubilized slurry.  
   
   
       42 . The method according to  claim 41 , wherein said stabilized kaolin slurry has a 28-day pour test result of at least 80% poured.  
   
   
       43 . The method according to  claim 42 , wherein said stabilized kaolin slurry has a 28-day pour test result of at least 85% poured.  
   
   
       44 . The method according to  claim 43 , wherein said stabilized kaolin slurry has a 28-day pour test result of at least 89% poured.  
   
   
       45 . The method according to  claim 41 , wherein said resulting kaolin has a conductivity of no more than about 80 μS.  
   
   
       46 . The method according to  claim 41 , wherein said slurry comprises kaolin having no more than about 80% by weight of particles having an equivalent spherical diameter (ESD) of less than 2 microns.  
   
   
       47 . The method according to  claim 46 , wherein said slurry comprises kaolin having about 25% to about 70% by weight particles having an ESD of less than 2 microns.  
   
   
       48 . The method according to  claim 46 , wherein said slurry comprises kaolin having about 20% to about 65% by weight particles having an ESD of less than 2 microns.  
   
   
       49 . (canceled)  
   
   
       50 . The method according to  claim 48 , wherein said slurry comprises kaolin having about 25% to about 45% by weight particles having an ESD of less than 2 microns.  
   
   
       51 . (canceled)  
   
   
       52 . The method according to  claim 50 , wherein said slurry comprises kaolin having about 35% by weight particles having an ESD of less than 2 microns.  
   
   
       53 . The method according to  claim 41 , wherein said slurry comprises kaolin having a shape factor of at least 25.  
   
   
       54 . The method according to  claim 41 , wherein said at least one stabilizer comprises carboxymethylcellulose.  
   
   
       55 . The method according to  claim 41 , wherein said at least one stabilizer comprises at least one cellulosic thickener chosen from alkyl celluloses, ethyl hydroxyethyl celluloses, hydroxymethyl celluloses, hydroxyethyl celluloses, and hydroxypropyl celluloses.  
   
   
       56 . The method according to  claim 41 , wherein said at least one stabilizer is chosen from montmorillonite, smectite clays, hydrophobically modified ethoxylated urethanes, polyacrylates, polyvinyl pyrrolidone, sodium alginate, xanthan gum, silica thickeners, sodium magnesium silicate, acrylic acid copolymers, and nonionic hydrophobically modified polyethers.  
   
   
       57 . The method according to  claim 41 , wherein said at least one stabilizer is present in an amount ranging from about 0.01% to about 4% by weight, relative to the total weight of the slurry.  
   
   
       58 . The method according to  claim 41 , wherein substantially no dispersant is added to said slurry.  
   
   
       59 . The method according to  claim 41 , further comprising adding at least one dispersant.  
   
   
       60 . The method according to  claim 59 , wherein the at least one dispersant is chosen from polyacrylates, polyphosphates, and silicates.  
   
   
       61 . (canceled)  
   
   
       62 . The method according to  claim 59 , wherein the at least one dispersant is present in an amount ranging from about 100 ppm to about 500 ppm on a dry basis relative to the total weight of the slurry.  
   
   
       63 . The method according to  claim 41 , further comprising flocculating said kaolin slurry prior to said filtering and rinsing.  
   
   
       64 . The method according to  claim 63 , wherein said flocculation comprises lowering the pH of said kaolin slurry to a value of about 5 or less.  
   
   
       65 . The method according to  claim 41 , further comprising spray drying said kaolin slurry prior to said filtering and rinsing.  
   
   
       66 - 68 . (canceled)  
   
   
       69 . A method for improving the stability of a kaolin slurry comprising: filtering and rinsing a kaolin slurry with water to remove salt residue therefrom, wherein said kaolin slurry comprises kaolin having no more than about 80% by weight particles having an ESD of less than 2 microns; and adding an effective amount of at least one stabilizer, wherein the stabilized kaolin slurry has a 28-day pour test result of at least 80% poured.  
   
   
       70 - 76 . (canceled)  
   
   
       77 . The method according to claim  94 , further comprising adding at least one dispersant to said slurry.  
   
   
       78 . (canceled)  
   
   
       79 . The method according to  claim 77 , wherein the at least one dispersant is present in an amount ranging from about 100 ppm to about 500 ppm on a dry basis relative to the total weight of the slurry.  
   
   
       80 . The method according to  claim 77 , wherein said at least one dispersant is chosen from polyacrylates, polyphosphates, and silicates.  
   
   
       81 . The method according to claim  94 , wherein said stabilized kaolin slurry has a Brookfield viscosity at 50% adjusted solids ranging from about 300 cps to about 700 cps using a #2 spindle at 20 rpm.  
   
   
       82 . (canceled)  
   
   
       83 . The method according to claim  94 , wherein said stabilized kaolin slurry has a Hercules viscosity at 50% adjusted solids of less than about 10 dynes at 4400 rpm using an “A” bob.  
   
   
       84 . The method according to claim  94 , wherein said slurry comprises kaolin having about 25% to about 70% by weight particles having an ESD of less than 2 microns.  
   
   
       85 - 86 . (canceled)  
   
   
       87 . The method according to  claim 84 , wherein said slurry comprises kaolin having about 25% to about 45% by weight particles having an ESD of less than 2 microns.  
   
   
       88 . (canceled)  
   
   
       89 . The method according to  claim 87 , wherein said slurry comprises kaolin having about 35% by weight particles having an ESD of less than 2 microns  
   
   
       90 . (canceled)  
   
   
       91 . The method according to claim  94 , wherein said stabilized kaolin slurry has a 28-day pour test result of at least about 85% poured.  
   
   
       92 . The method according to  claim 91 , wherein said stabilized kaolin slurry has a 28-day pour test result of at least about 89% poured.