Process and chemistry for reducing dolomite concentrations in phosphate processing

Abstract

A magnesium suppressant/flocculant for use in separating dolomite from calcium phosphate. The magnesium suppressant/flocculant may be applied at a mine site prior to subjecting ore fractions to phosphate flotation or at a chemical plant after grinding.

What is claimed is: 
     
         1 . A magnesium suppressant/flocculant for use in reducing dolomite concentrations in phosphate processing, where the magnesium suppressant/flocculant is a polymer comprising:
 a base monomer comprising acrylic acid, acrylamide, or a combination of acrylic acid and acrylamide; and   a functional monomer comprising hydroxyl ethyl methacrylate, 2-acrylamido-2-methyl propane sulfonic acid, 3-allyloxy-1, 2-propanediol, and/or a derivative thereof.   
     
     
         2 . The magnesium suppressant/flocculant of  claim 1  where the molecular weight of the polymer is 3,000 daltons to 30,000 daltons. 
     
     
         3 . The magnesium suppressant/flocculant of  claim 1  where the molecular weight of the polymer is 200,000 daltons to 100,000,000 daltons. 
     
     
         4 . The magnesium suppressant/flocculant of  claim 1  where the charge of the functional monomer is 10% to 30%. 
     
     
         5 . A method of reducing dolomite concentrations in phosphate processing, the method comprising:
 adding a magnesium suppressant to phosphate-containing fractions;   conditioning the fractions with fatty acid; and   subjecting the fractions to a phosphate flotation.   
     
     
         6 . The method of  claim 5  where the magnesium suppressant is a polymer comprising:
 a base monomer comprising acrylic acid, acrylamide, or a combination of acrylic acid and acrylamide; and 
 a functional monomer comprising hydroxyl ethyl methacrylate, 2-acrylamido-2-methyl propane sulfonic acid, 3-allyloxy-1, 2-propanediol, and/or a derivative thereof. 
 
     
     
         7 . The method of  claim 5  where adding the magnesium suppressant to the fractions prevents magnesium within the fractions from interacting with the fatty acid, which minimizes the extent to which the magnesium interacts with hydrophobic bubbles during the phosphate flotation. 
     
     
         8 . The method of  claim 5  further comprising grinding the fractions prior to adding the magnesium suppressant. 
     
     
         9 . The method of  claim 8  where the grinding results in a particle size of less than 100 microns. 
     
     
         10 . A method of reducing dolomite concentrations in phosphate processing, the method comprising:
 adding magnesium flocculant to phosphate rock during processing at a chemical plant.   
     
     
         11 . The method of  claim 10  where the magnesium flocculant is a polymer comprising:
 a base monomer comprising acrylic acid, acrylamide, or a combination of acrylic acid and acrylamide; and 
 a functional monomer comprising hydroxyl ethyl methacrylate, 2-acrylamido-2-methyl propane sulfonic acid, 3-allyloxy-1, 2-propanediol, and/or a derivative thereof. 
 
     
     
         12 . The method of  claim 10 , further comprising:
 transferring the phosphate rock to a clarifier or thickener, where the magnesium flocculant selectively flocculates dolomite in the phosphate rock such that the dolomite settles to the bottom of the clarifier or thickener; and   removing the dolomite from the bottom of the clarifier or thickener.   
     
     
         13 . The method of  claim 10 , further comprising rinsing the phosphate rock with pond water to extract soluble magnesium prior to adding the magnesium flocculant. 
     
     
         14 . The method of  claim 13 , further comprising adding coagulant with the magnesium flocculant. 
     
     
         15 . The method of  claim 10 , further comprising grinding the fractions prior to adding the magnesium flocculant. 
     
     
         16 . The method of  claim 15  where the grinding results in a particle size of less than 100 microns.