Surface mineralized organic fibers and methods of making the same

Abstract

A method of making a mineralized fiber having a fiber core and a calcium carbonate shell can include admixing fibers with green liquor and adding CaO to generate a causticization reaction that results in a calcium carbonate shell coating forming around the fibers.

1 . A mineralized fiber comprising:
 a fiber defining a core of the surface mineralized fiber, and   calcium carbonate surrounding the core and infiltrated into the fiber, wherein the calcium carbonate increases the bending stiffness of the fiber.   
     
     
         2 . The mineralized fiber of  claim 1 , wherein the fiber has a hollow interior and the calcium carbonate infiltrates into and the hollow interior. 
     
     
         3 . The mineralized fiber of  claim 1 , wherein the calcium carbonate infiltrates into the fiber such that at least a portion of surface strands of the fiber are encapsulated by calcium carbonate. 
     
     
         4 . The mineralized fiber of  claim 1 , wherein the fiber has a specific surface area of about 2 m 2 /g to about 80 m 2 /g. 
     
     
         5 . The mineralized fiber of  claim 1 , wherein the fibers are pulp from one or more of Eucalyptus, Birch, Acacia, Aspen, Pine, Spruce, and old corrugated cardboard recycled fiber. 
     
     
         6 . A method of making a mineralized fiber, comprising:
 admixing fibers with Na 2 CO 3  form a fiber slurry;   adding dry CaO to the fiber slurry in an amount such that the stoichiometric amount of CaO is less than the stoichiometric amount of sodium carbonate presented in the fiber slurry and admixing for a time sufficient to allow the CaO to react with the sodium carbonate in a causticization reaction, thereby forming the surface mineralized fibers comprising a fiber core with calcium carbonate surrounding the core and infiltrating into the fiber.   
     
     
         7 . The method of  claim 6 , further comprising passing the surface mineralized fibers resulting with the admixture of the dry CaO with the fiber slurry over a screen to separate the surface mineralized fibers from excess calcium carbonate and NaOH produced during the causticization reaction and washing the separated surface mineralized fibers with water to remove excess calcium carbonate. 
     
     
         8 . The method of  claim 7 , wherein the screen is a 230 mesh screen. 
     
     
         9 . The method of  claim 6 , wherein the fibers are pulp from one or more of Eucalyptus, Birch, Acacia, Aspen, Pine, Spruce, and old corrugated cardboard recycled fiber 
     
     
         10 . The method of  claim 6 , wherein the fibers are pulp from a kraft process and the Na 2 CO 3  is provided as green liquor (Na 2 CO 3 /Na 2 S/H 2 O) from the kraft process. 
     
     
         11 . The method of  claim 10 , further comprising passing the surface mineralized fibers resulting with the admixture of the dry CaO with the fiber slurry over a screen to separate the surface mineralized fibers from excess calcium carbonate and NaOH/Na 2 S/H 2 O produced during the causticization reaction and washing the separated surface mineralized fibers with water to remove excess calcium carbonate, and recycling the NaOH/Na 2 S/H 2 O, excess calcium carbonate, and collected wash solution into the kraft process. 
     
     
         12 . The method of  claim 11 , wherein the screen is a 230 mesh screen. 
     
     
         13 . The method of  claim 6 , wherein the fibers are provided as an aqueous slurry. 
     
     
         14 . The method of  claim 6 , wherein the fibers and the NaOH/Na 2 S/H 2 O are admixed while heating to a temperature of about 70° C. to about 105° C. 
     
     
         15 . The method of  claim 6 , wherein the dry CaO and the fiber slurry are admixed while maintaining a temperature of about 70° C. to about 105° C. 
     
     
         16 . The method of  claim 6 , wherein the fiber is a refined fiber refined to a level of 20 SR to 90 SR.