Coal drying method and system

Abstract

The present invention provides methods and systems for reducing moisture in coal, particularly coal fines and other coal streams comprising small diameter particles, using a granular drying material. The invention also relates to novel coal products and intermediates useful in connection with the process. The method and system reduced moisture by contacting the coal with the granular drying material. The granular drying material is selected to be readily separated from the coal fines using a size separation technique such as a sieve screen. The granular drying material is the regenerated, preferably using a process involving heat exchange and cross-flow air. The granular drying material is preferably capable of regeneration and recycling in a continuous process with minimal attrition.

1 . A method for reducing coal moisture comprising:
 (a) contacting a first volume of coal with a second volume of granular drying media;   (b) reducing the moisture content of the coal by transferring moisture from the coal to the granular drying media; and   (c) separating the granular drying media from the coal by difference in particle size.   
     
     
         2 . The method of  claim 1 , wherein the first volume of coal has greater than 10% of particles of a diameter less than the average diameter of the granular drying media. 
     
     
         3 . The method of  claim 1 , wherein the first volume of coal has greater than 10% of particles smaller than 28 mesh. 
     
     
         4 . The method of  claim 1 , wherein the first volume of coal has greater than 50% of particles smaller than 28 mesh. 
     
     
         5 . The method of  claim 1 , wherein the first volume of coal has greater than 80% of particles smaller than 28 mesh. 
     
     
         6 . The method of  claim 1 , wherein the moisture content of the first volume of coal is greater than 20% by weight, and the moisture content of the coal is less than 10% by weight after step (c). 
     
     
         7 . The method of  claim 1 , wherein the granular drying media is spherical has a mean particle diameter ranging from approximately 2.0 mm to approximately 4.7 mm. 
     
     
         8 . The method of  claim 1 , wherein the granular drying media is spherical has a mean particle diameter of approximately 3.2 mm. 
     
     
         9 . The method of  claim 1 , wherein the granular drying media has a crush strength that exceeds 25 lbf. 
     
     
         10 . The method of  claim 1 , wherein the granular drying media has a surface area of greater than or equal to 340 m 2 /g. 
     
     
         11 . The method of  claim 1 , wherein first volume of coal is primarily coal fines. 
     
     
         12 . The method of  claim 1 , wherein first volume of coal is primarily coal fine refuse. 
     
     
         13 . The method of  claim 1 , wherein the first volume of coal has been subjected to a size separation step prior to step (a). 
     
     
         14 . The method of  claim 1 , wherein the first volume of coal has been subjected to a moisture reduction step prior to step (a). 
     
     
         15 . The method of  claim 1 , wherein the second volume of granular drying media comprises a molecular sieve, a hydratable polymer, a dessicant or a mixture thereof. 
     
     
         16 . The method of  claim 1 , wherein the second volume of granular drying media comprises activated alumina. 
     
     
         17 . The method of  claim 1 , wherein step (c) is conducted using a sieve screen. 
     
     
         18 . The method of  claim 1 , further comprising a step (d) of regenerating the granular drying media after step (c). 
     
     
         19 . The method of  claim 1 , wherein the process is continuous and at least a portion of the second volume of granular drying media is subjected to a step (d) of regenerating the granular drying media after step (c). 
     
     
         20 . The method of  claim 18 , wherein the step (d) of regenerating the granular drying media utilizes a combination of heat exchange and cross-flow air. 
     
     
         21 . A system for reducing coal moisture comprising:
 (a) a combination unit for contacting a first volume of coal and a second volume of granular drying media to transfer moisture from the coal to the granular drying media;   (b) a separation unit for separating the granular drying material from the coal by difference in particle size.   (c) a regeneration unit for removing moisture from the granular drying media.   
     
     
         22 .- 40 . (canceled) 
     
     
         41 . A composition comprising a mixture of a volume of granular drying media and a volume of coal, wherein the granular drying media is in a form that can be readily separated from the volume of coal by size. 
     
     
         42 . A coal composition comprising:
 (a) coal having a moisture content below 10% by weight; and   (b) an amount of drying media residue, wherein the amount of drying media residue is less than 0.5% by weight of the composition.   
     
     
         43 .- 48 . (canceled) 
     
     
         49 . A method for reducing coal moisture comprising:
 (a) contacting a first volume of coal with a second volume of granular drying media;   (b) reducing the moisture content of the coal by transferring moisture from the coal to the granular drying media; and   (c) separating the granular drying media from the coal by difference in magnetic properties.   
     
     
         50 . (canceled)