Grinding method

Abstract

The invention provides a method of grinding an inorganic particulate material such as calcium carbonate or kaolin in an aqueous suspension, preferably at a solids level below about 50% by weight, wherein the aqueous suspension includes a sub-effective amount of a dispersing agent for the inorganic particulate material.

1 - 38 . (canceled)  
   
   
       39 . A method of grinding an inorganic particulate material in an aqueous suspension, said aqueous suspension comprising a sub-effective amount of at least one dispersant for the inorganic particulate material.  
   
   
       40 . A method according to  claim 39 , wherein the inorganic particulate material comprises calcium carbonate.  
   
   
       41 . A method according to  claim 39 , wherein the inorganic particulate material comprises hydrous kandite clays.  
   
   
       42 . A method according to  claim 41 , wherein the hydrous kandite clays comprise kaolins.  
   
   
       43 . A method according to  claim 39 , wherein the aqueous suspension comprises up to about 50% by weight of the inorganic particulate material.  
   
   
       44 . A method according to  claim 39 , wherein the aqueous suspension comprises up to about 0.25% by weight of the at least one dispersant, based on the dry weight of the inorganic particulate material.  
   
   
       45 . A method according to  claim 44 , wherein the aqueous suspension comprises up to about 0.15% by weight of the at least one dispersant, based on the dry weight of the inorganic particulate material.  
   
   
       46 . A method according to  claim 45 , wherein the aqueous suspension comprises up to about 0.1% by weight of the at least one dispersant, based on the dry weight of the inorganic particulate material.  
   
   
       47 . A method according to  claim 46 , wherein the aqueous suspension comprises up to about 0.05% by weight of the at least one dispersant, based on the dry weight of the inorganic particulate material.  
   
   
       48 . A method according to  claim 39 , wherein the at least one dispersant is chosen from polyacrylates.  
   
   
       49 . A method according to  claim 39 , wherein the at least one dispersant is chosen from polymetaphosphates.  
   
   
       50 . A method according to  claim 49 , wherein the polymetaphosphate is chosen from sodium hexametaphosphate and tetrasodium metaphosphate.  
   
   
       51 . A method according to  claim 39 , wherein, after grinding, an additional amount of a dispersant is added to the aqueous suspension.  
   
   
       52 . A method according to  claim 39 , wherein, after grinding, an amount of water is removed from the aqueous suspension.  
   
   
       53 . A method according to  claim 39 , further comprising adjusting the solids level of the aqueous suspension after grinding to provide an aqueous suspension comprising the inorganic particulate material at a solids level above about 50% by weight, based on the total weight of the suspension.  
   
   
       54 . A method according to  claim 39 , wherein, after grinding, the inorganic particulate material has a steepness factor above about 35.  
   
   
       55 . A method according to  claim 54 , wherein, after grinding, the inorganic particulate material has a steepness factor above about 40.  
   
   
       56 . A method according to  claim 55 , wherein, after grinding, the inorganic particulate material has a steepness factor above about 45.  
   
   
       57 . A method according to  claim 39 , wherein, after grinding, the inorganic particulate matter has an increased steepness.  
   
   
       58 . A method according to  claim 39 , further comprising dewatering the aqueous suspension after grinding, to achieve a solids content above about 50% by weight of the inorganic particulate material.  
   
   
       59 . A method according to  claim 39 , wherein the resultant ground inorganic particulate material is dried after treatment.  
   
   
       60 . A method according to  claim 39 , wherein the resultant ground inorganic particulate material is added to: 
 a paper or paper pulp to provide a coating or filler therefore, and/or    a composition which is subsequently processed to obtain a paper.    
   
   
       61 . A method according to  claim 39 , wherein the resultant ground inorganic particulate material is added to: 
 a polymer or rubber, and/or    to a composition which is subsequently processed to obtain a polymer or rubber.    
   
   
       62 . A method according to  claim 61 , wherein the polymer is a plastics material.  
   
   
       63 . A method according to  claim 61 , wherein the resultant polymer is formed into a film.  
   
   
       64 . A method according to  claim 39 , wherein the resultant ground inorganic particulate material is added to: 
 a paint, and/or    a composition which is subsequently processed to obtain a paint.    
   
   
       65 . A method according to  claim 39 , wherein the resultant ground inorganic particulate material is added to: 
 a sealant or mastic, and/or    a composition which is subsequently processed to obtain a sealant or mastic.    
   
   
       66 . A method according to  claim 39 , wherein the resultant ground inorganic particulate material is added to: 
 a ceramic, and/or    a composition which is subsequently processed to obtain a ceramic.    
   
   
       67 . An aqueous suspension of a ground inorganic particulate material comprising a sub-effective amount of a dispersant for the inorganic particulate material.  
   
   
       68 . An aqueous suspension of a ground inorganic particulate material comprising a sub-effective amount of a dispersant for the at least one inorganic particulate material prepared by a method of grinding an inorganic particulate material in an aqueous suspension, wherein said aqueous suspension comprises a sub-effective amount of at least one dispersant for the inorganic particulate material.  
   
   
       69 . An aqueous suspension of a ground inorganic particulate material comprising a dispersant-effective amount of a dispersant for the inorganic particulate material, wherein said aqueous suspension is prepared by a method of grinding an inorganic particulate material in an aqueous suspension, said aqueous suspension comprising a sub-effective amount of at least one dispersant for the inorganic particulate material and adding, after grinding, a dispersant to the aqueous suspension.  
   
   
       70 . A dry ground inorganic particulate material comprising an amount of a dispersant for the inorganic particulate material, the material being the dry residue of an aqueous suspension according to  claim 67 .  
   
   
       71 . A dry ground inorganic particulate material comprising an amount of a dispersant for the inorganic particulate material, the material being the dry residue of an aqueous suspension according to  claim 68 .  
   
   
       72 . A dry ground inorganic particulate material comprising an amount of a dispersant for the inorganic particulate material, the material being the dry residue of an aqueous suspension according to  claim 69 .  
   
   
       73 . A paper or paper pulp, when prepared by a method according to  claim 60 .  
   
   
       74 . A polymer or rubber, when prepared by a method according to  claim 61 .  
   
   
       75 . A paint, when prepared by a method according to  claim 64   
   
   
       76 . A sealant or mastic, when prepared by a method according to  claim 65 .  
   
   
       77 . A ceramic, when prepared by a method according to  claim 66 .  
   
   
       78 . A process of inhibiting corrosion in a low solids aqueous suspension of inorganic particulate material comprising the addition of a sub-effective amount of at least one dispersant for said inorganic particulate material as a corrosion inhibitor in a low solids aqueous suspension.