Treating slurries

Abstract

This invention relates to a composition for treating inorganic slurries and to a method of treating inorganic slurries with the aforesaid composition so as to maintain the slurries in a substantially homogeneous phase. The composition comprises a THP + salt and a dispersant selected from the group consisting of: (i) phosphonated compound containing at least one tertiary nitrogen atom; (ii) phosphonated oligomers of unsaturated acids; (iii) homopolymers of unsaturated acids; and (iv) Polyphosphates The THP + salt is preferably THPS

1 - 19 . (canceled)  
   
   
       20 . A method for treating an inorganic slurry to maintain the slurry in a substantially homogeneous phase and to preserve the slurry against bacterial contamination, which comprises the addition to the slurry of an effective amount of a composition comprising: 
 (a) a tetrakis(hydroxyorgano)phosphonium salt (herein THP +  salt) selected from tetrakis(hydroxymethyl)phosphonium sulphate, tetrakis(hydroxymethyl)phosphonium chloride, tetrakis(hydroxymethyl)phosphonium phosphate, tetrakis(hydroxymethyl)phosphonium nitrate and tetrakis(hydroxymethyl)phosphonium oxalate; and    (b) a dispersant selected from the group consisting of: 
 (i) phosphonated compounds containing at least one tertiary nitrogen atom; and  
 (ii) homopolymers of unsaturated acids.  
   
   
   
       21 . A method according to  claim 20 , in which the THP +  salt is tetrakis(hydroxymethyl)phosphonium sulphate.  
   
   
       22 . A method according to  claim 20 , in which the THP +  salt is tetrakis(hydroxymethyl)phosphonium chloride, phosphate, nitrate or oxalate.  
   
   
       23 . A method according to  claim 20 , in which the dispersant (b(i)) is a phosphonated compound containing one tertiary nitrogen atom.  
   
   
       24 . A method according to claim  4 , in which the dispersant (b(i)) is a sodium salt of nitrilo-tris(methylene phosphonate).  
   
   
       25 . A method according to claim  5 , in which the salt is the tetra-sodium salt.  
   
   
       26 . A method according to  claim 20 , in which the dispersant (b(ii)) is a homopolymer of acrylic acid.  
   
   
       27 . A method according to  claim 26 , in which the homopolymer has a molecular weight in the range 2000 to 5000.  
   
   
       28 . A method according to  claim 20 , in which the ratio of THP +  salt to dispersant in the composition is about 2:1 (as active ingredients).  
   
   
       29 . A method according to  claim 20 , in which the composition is added to the slurry in an amount in the range 10 ppm to 1000 ppm (by weight of the slurry).  
   
   
       30 . A method according to  claim 20 , in which the composition is added to the slurry in an amount of about 750 ppm (by weight of the slurry).  
   
   
       31 . A method, according to  claim 20 , in which the slurry comprises a calcium carbonate-based slurry.  
   
   
       32 . A method according to  claim 20 , in which the slurry comprises a pigment slurry, a clay slurry or a cement slurry.  
   
   
       33 . A composition for treating an inorganic slurry, the composition comprising: 
 (a) tetrakis(hydroxyorgano)phosphonium salt (herein THP +  salt) selected from tetrakis(hydroxymethyl)phosphonium sulphate, tetrakis(hydroxymethyl)phosphonium chloride, tetrakis(hydroxymethyl)phosphonium phosphate, tetrakis(hydroxymethyl)phosphonium nitrate and tetrakis(hydroxymethyl)phosphonium oxalate; and    (b) a dispersant which is the tetra sodium salt of nitrilo-tris (methylene phosphonate).    
   
   
       34 . A composition according to  claim 33 , wherein the THP +  salt is tetrakis(hydroxymethyl)phosphonium sulphate.  
   
   
       35 . A method of treating an inorganic slurry to maintain the slurry in a substantially homogeneous phase and to preserve the slurry against bacterial contamination, comprising the addition to the slurry of an effective amount of a composition according to  claim 33 .  
   
   
       36 . A composition for treating an inorganic slurry, the composition comprising: 
 (a) a tetrakis(hydroxymethyl)phosphonium salt (herein THP +  salt) selected from tetrakis(hydroxymethyl)phosphonium sulphate, tetrakis (hydroxymethyl)phosphonium chloride, tetrakis(hydroxymethyl)phosphonium phosphate, tetrakis(hydroxymethyl)phosphonium nitrate and tetrakis(hydroxymethyl)phosphonium oxalate; and    (b) a dispersant which is a homopolymer of acrylic acid, the homopolymer having a molecular weight in the range of 2,000 to 5,000.    
   
   
       37 . A composition according to  claim 36 , wherein the THP +  salt is tetrakis(hydroxymethyl)phosphonium sulphate.  
   
   
       38 . A method of treating an inorganic slurry to maintain the slurry in a substantially homogeneous phase and to preserve the slurry against bacterial contamination, comprising the addition to the slurry of an effective amount of a composition according to  claim 36.