Plenum crusher dust injection

Abstract

Methods for heating a solid material comprising a granular material are provided. Dust is removed from the granular material before it is heated. The dust is injected into the exhaust gas from the heater. The heated dust is recovered and combined with the heated granular material.

1 . In a process for heating a solid material comprising a granular material using a kiln, the improvement comprising:
 injecting a dust material into an exhaust gas stream which exits an outlet of the kiln and enters a first particulate capture device; wherein the exhaust gas stream is of a temperature sufficient to affect a desired change in the dust material; and   recovering a recovered dust material from the first particulate capture device.   
     
     
         2 . The process of  claim 1 , further comprising introducing the recovered dust material with a heated granular material for further processing. 
     
     
         3 . The process of  claim 1 , wherein the exhaust gas stream is of a temperature sufficient to dry or calcine the dust material. 
     
     
         4 . The process of  claim 1 , wherein the dust material is derived from an ore. 
     
     
         5 . The process of  claim 1 , wherein the dust material is lime, cement, gypsum, coal or a mineral. 
     
     
         6 . The process of  claim 1 , wherein the kiln is a rotary type-kiln. 
     
     
         7 . The process of  claim 1 , further comprising:
 crushing the solid material to form the dust material and the granular material;   separating the dust material from the granular material;   injecting the granular material into the kiln; and   heating the granular material.   
     
     
         8 . The process of  claim 7 , wherein the solid material is lime, cement, gypsum, coal or a mineral. 
     
     
         9 . The process of  claim 8 , wherein the solid material is trona. 
     
     
         10 . The process of  claim 1 , wherein at least 90 wt % of the dust material has a particle size less than 100 mesh, and at least 90 wt. % of the granular material has a particle size greater than 100 mesh. 
     
     
         11 . The process of  claim 1  wherein the temperature of the exhaust gas stream exiting the calciner is between about 300° F. and about 500° F. 
     
     
         12 . The process of  claim 1 , further comprising:
 crushing the solid material in a crusher device to form the dust material;   collecting the dust material from the crusher device in a second particulate capture device; and   pneumatically transferring the dust material from the second particulate capture device to the exhaust gas stream.   
     
     
         13 . A process for heating a solid material comprising:
 a. removing a dust material from a solid material comprising a granular material and a dust material, said dust material having a particle size smaller than a particle size of the granular material;   b. introducing the granular material into a heater;   c. heating the granular material in the heater;   d. injecting the dust material into an exhaust gas stream from the heater; and   e. recovering the injected dust material.   
     
     
         14 . The process of  claim 13 , wherein the heater is a rotary type-kiln. 
     
     
         15 . The process of  claim 13 , further comprising:
 capturing the dust material from the solid material in a particulate capture device; and   pneumatically transferring the dust material from the particulate capture device to the exhaust gas stream.   
     
     
         16 . The process of  claim 13 , further comprising introducing the dust material into the exhaust gas stream in a plenum of the particulate capture device. 
     
     
         17 . In a process for heating a solid material comprising a granular material using a kiln, the improvement comprising:
 separating the solid material into a fine particle size part and a coarse particle size part;   injecting the coarse particle size part at a first location of the kiln, wherein the first location is at the hot end of the kiln; and   injecting the fine particle size part at a second location of the kiln, wherein the second location is downstream of the first location.   
     
     
         18 . The process of  claim 17 , further comprising introducing a flame at the first location of the kiln, and wherein the second location is downstream of the flame. 
     
     
         19 . The process of  claim 18 , wherein the second location is at the cool end of the kiln. 
     
     
         20 . The process of  claim 18 , wherein the second location is an exhaust duct exiting the kiln.