Methods for production of pitch particles with reprocessing of pitch fines

Abstract

Pitch particles may be produced by a grinding process, in which pitch fines may be recovered and recycled to a grinding apparatus as a pitch melt. Such methods may comprise: providing a petroleum pitch having a first softening temperature; grinding the petroleum pitch in a grinding apparatus below the first softening temperature to produce a plurality of pitch particles and a plurality of pitch fines; separating the pitch particles from the pitch fines; heating the pitch fines at a temperature above the first softening temperature to produce a pitch melt; and combining the pitch melt with the petroleum pitch in the grinding apparatus. The pitch melt hardens in the grinding apparatus and is reground. The pitch particles may be further stabilized by heating at a treatment temperature below the first softening temperature in an environment comprising about 1 mol % to about 20 mol % oxygen to form stabilized pitch particles.

What is claimed is: 
     
         1 . A method comprising:
 providing a petroleum pitch having a first softening temperature;   grinding the petroleum pitch in a grinding apparatus below the first softening temperature to produce a plurality of pitch particles and a plurality of pitch fines;   separating the pitch particles from the pitch fines;   heating the pitch fines at a temperature above the first softening temperature to produce a pitch melt; and   combining the pitch melt with the petroleum pitch in the grinding apparatus,
 wherein the pitch melt hardens in or before the grinding apparatus and is reground. 
   
     
     
         2 . The method of  claim 1 , wherein the first softening temperature is in a range from about 180° C. to about 500° C. 
     
     
         3 . The method of  claim 1 , wherein the pitch particles having a particle size ranging from about 1 micron to about 25 microns. 
     
     
         4 . The method of  claim 1 , wherein the grinding is performed using a jet, impact, or ball mill. 
     
     
         5 . The method of  claim 1 , further comprising:
 heating the pitch particles at a treatment temperature below the first softening temperature in an environment comprising about 1 mol % to about 20 mol % oxygen to form stabilized pitch particles,
 wherein the stabilized pitch particles have second softening temperature that is higher than the first softening temperature. 
   
     
     
         6 . The method of  claim 5 , wherein the treatment temperature is at least about 5° C. below the first softening temperature. 
     
     
         7 . The method of  claim 5 , wherein heating is conducted over a time period of about 10 minutes to about 6 hours. 
     
     
         8 . The method of  claim 1 , further comprising:
 heating the pitch particles at a carbonization temperature in an environment comprising about 0.1 mol % oxygen or below.   
     
     
         9 . The method of  claim 8 , wherein the carbonization temperature is in a range of from about 700° C. to about 1800° C. 
     
     
         10 . The method of  claim 8 , further comprising:
 heating the pitch particles at a graphitization temperature in an environment comprising about 0.1 mol % oxygen or below.   
     
     
         11 . The method of  claim 10 , wherein the graphitization temperature is in a range of from about 2000° C. to about 3400° C. 
     
     
         12 . The method of  claim 1 , further comprising:
 introducing one or more additives to the pitch melt.   
     
     
         13 . The method of  claim 1 , wherein the petroleum pitch comprises about 50 wt % or greater mesophase pitch. 
     
     
         14 . The method of  claim 1 , wherein the pitch fines have a particle size of about 1 micron or less. 
     
     
         15 . The method of  claim 1 , further comprising:
 performing a size separation of the pitch particles after separating the pitch particles from the pitch fines;
 wherein rejected pitch particles are removed in the size separation; and 
   combining the rejected pitch particles with the pitch fines to form the pitch melt.   
     
     
         16 . A method comprising:
 providing a petroleum pitch having a first softening temperature of about 180° C. to about 500° C.;   grinding the petroleum pitch in a grinding apparatus below the first softening temperature to produce a plurality of pitch particles and a plurality of pitch fines;   separating the pitch particles from the pitch fines;   heating the pitch fines at a temperature above the first softening temperature to produce a pitch melt;   combining the pitch melt with the petroleum pitch in the grinding apparatus;
 wherein the pitch melt hardens in or before the grinding apparatus and is reground; and 
   heating the pitch particles at a treatment temperature below the first softening temperature in an environment comprising about 1 mol % to about 20 mol % oxygen to form stabilized pitch particles,
 wherein the stabilized pitch particles have second softening temperature that is higher than the first softening temperature. 
   
     
     
         17 . The method of  claim 16 , wherein the treatment temperature is at least about 5° C. below the first softening temperature. 
     
     
         18 . The method of  claim 16 , wherein the pitch particles having a particle size ranging from about 1 microns to about 25 microns. 
     
     
         19 . The method of  claim 16 , wherein the grinding is performed using a jet, impact, or ball mill. 
     
     
         20 . The method of  claim 16 , further comprising:
 performing a size separation of the pitch particles after separating the pitch particles from the pitch fines;
 wherein rejected pitch particles are removed in the size separation; and 
   combining the rejected pitch particles with the pitch fines to form the pitch melt.