Processing of low rank coal

Abstract

A method of processing coal includes placing coal having a heat content between about 3,000 BTU/lb and about 9,000 BTU/lb and a moisture content between about 20 wt % and about 60 wt % in a vessel. The coal is heated by conduction. A pressure in the vessel is reduced to below atmospheric pressure, thereby reducing the coal, such that an average primary particle size of the coal is less than 1 millimeter. The reduced coal is shaped to yield a fuel composition.

1 .- 20 . (canceled) 
     
     
         21 . A method of processing coal, the method comprising:
 placing coal having a first heat content in a vessel;   heating the coal;   reducing a pressure in the vessel to below atmospheric pressure by pulling vapor from a vapor space of the vessel using a vacuum pump, thereby reducing the coal; and   shaping the reduced coal to yield a fuel composition having a second heat content different from the first heat content of the coal.   
     
     
         22 . The method of  claim 21 , wherein heating the coal comprises contacting the coal with a heated surface. 
     
     
         23 . The method of  claim 22 , wherein the heated surface comprises a rotating blade. 
     
     
         24 . The method of  claim 23 , wherein the rotating blade rotates at a rate between 2 and 25 revolutions per minute. 
     
     
         25 . The method of  claim 21 , wherein heating the coal comprises heating the coal to a temperature between 30° C. and 100° C. 
     
     
         26 . The method of  claim 21 , wherein heating the coal comprises heating the coal to a temperature up to about 250° C. 
     
     
         27 . The method of  claim 21 , wherein heating the coal comprises heating the coal to a temperature between 100° C. and 250° C. 
     
     
         28 . The method of  claim 21 , further comprising agitating the coal in the vessel by contacting the coal with a rotating blade. 
     
     
         29 . The method of  claim 21 , further comprising intermittently agitating the coal in the vessel. 
     
     
         30 . The method of  claim 21 , wherein reducing the pressure in the vessel comprises intermittently reducing the pressure in the vessel. 
     
     
         31 . The method of  claim 21 , wherein reducing the pressure in the vessel comprises reducing the pressure in the vessel to between 10 torr and 150 torr. 
     
     
         32 . The method of  claim 21 , wherein the coal placed in the vessel is uncrushed. 
     
     
         33 . The method of  claim 21 , wherein the coal placed in the vessel comprises lignite. 
     
     
         34 . The method of  claim 21 , wherein the coal placed in the vessel has a moisture content between 30 wt % and 60 wt %, or between 40 wt % and 50 wt %. 
     
     
         35 . The method of  claim 21 , wherein the fuel composition has a moisture content less than 3 wt %, less than 2 wt %, or less than 1 wt %. 
     
     
         36 . The method of  claim 21 , wherein the second heat content of the fuel composition is between 9,000 BTU/lb and 11,000 BTU/lb. 
     
     
         37 . The method of  claim 21 , wherein the coal is not pyrolyzed in the vessel. 
     
     
         38 . The method of  claim 21 , wherein the second heat content of the fuel composition is at least 1.5 to at least 1.9 times the first heat content of the coal. 
     
     
         39 . The method of  claim 21 , wherein the fuel composition is substantially free of fines. 
     
     
         40 . The method of  claim 21 , wherein shaping the reduced coal comprises:
 extruding the reduced coal to yield an extruded fuel product; and   cutting, shredding, or milling the extruded fuel product to form discrete portions of the fuel composition.