Pvoh binder compositions and methods for powdered minerals

Abstract

A slurry composition suitable for forming powdered mineral briquettes is disclosed. The composition comprises 4 wt % to 20 wt % of polyvinyl alcohol (PVOH) granules having a particle size distribution of less than 420 μm, 5 wt % to 9 wt % water, and the remainder comprising at least one powdered mineral. The composition may optionally include one or more additives. The total composition is 100 wt %, and the PVOH granules are added in dry form, without prior solubilization. Briquettes formed from the disclosed slurry exhibit improved green strength and compressive strength suitable for industrial handling and transport.

1 . A slurry composition for forming powdered mineral briquettes, comprising:
 4 wt % to 20 wt % of polyvinyl alcohol (PVOH) granules having a particle size distribution of less than 420 μm;   5 wt % to 9 wt % water; and   the remainder comprising a powdered mineral and, optionally, one or more additives, wherein the total composition is 100 wt %, and wherein the PVOH granules are not pre-solubilized.   
     
     
         2 . The slurry composition of  claim 1 , wherein the PVOH granules have a particle size distribution of less than 250 μm. 
     
     
         3 . The slurry composition of  claim 1 , wherein the PVOH granules have a particle size distribution of between 250 μm and 420 μm. 
     
     
         4 . The slurry composition of  claim 1 , wherein the PVOH granules have a particle size distribution of between 180 μm and 250 μm. 
     
     
         5 . The slurry composition of  claim 1 , wherein the PVOH granules have a molecular weight of between 15,000 g/mol and 210,000 g/mol. 
     
     
         6 . The slurry composition of  claim 1 , wherein the PVOH granules have a degree of hydrolysis of between 72% and 96.5%. 
     
     
         7 . The slurry composition of  claim 1 , wherein the PVOH granules have a degree of hydrolysis of between 82% and 96.5%. 
     
     
         8 . The slurry composition of  claim 1 , wherein the PVOH granules have a degree of hydrolysis of between 87% and 96.5%. 
     
     
         9 . The slurry composition of  claim 1 , wherein the one or more additives comprises starch, and wherein the starch is not pre-solubilized. 
     
     
         10 . The slurry composition of  claim 9 , wherein the PVOH granules have a degree of hydrolysis above 96.5%. 
     
     
         11 . The slurry composition of  claim 9 , comprising 5.5 wt % to 10 wt % of the starch. 
     
     
         12 . The slurry composition of  claim 9 , wherein the starch comprises partially hydrolyzed starch. 
     
     
         13 . A briquette formed from the slurry composition of  claim 1 , wherein the briquette exhibits a green strength pass rate of at least 60% as determined by the Green Strength Test. 
     
     
         14 . A briquette formed from the slurry composition of  claim 2 , wherein the briquette exhibits a green strength pass rate of 100% as determined by the Green Strength Test. 
     
     
         15 . A briquette formed from the slurry composition of  claim 1 , wherein the briquette exhibits a compressive strength of at least 2.7 MPa as determined by the Compressive Strength Test. 
     
     
         16 . A briquette formed from the slurry composition of  claim 1 , wherein the briquette exhibits an average weight loss of between 0.6% to 12.6% as determined by the Water Exposure Test. 
     
     
         17 . A method of forming powdered mineral briquettes, comprising:
 mixing polyvinyl alcohol (PVOH) granules having a particle size distribution of less than 420 μm, with powdered minerals and water in an amount sufficient to form a homogeneous slurry comprising 5 wt % to 9 wt % water and 4 wt % to 20 wt % of the PVOH; and   placing the homogeneous slurry into a mold and applying force to shape the slurry into briquettes.   
     
     
         18 . The method of  claim 17 , wherein the PVOH granules have a particle size distribution of less than 250 μm. 
     
     
         19 . The method of  claim 17 , wherein the PVOH granules have a molecular weight of between 15,000 g/mol and 210,000 g/mol. 
     
     
         20 . The method of  claim 17 , wherein the PVOH granules have a degree of hydrolysis of between 72% and 96.5%.