Carbonising and/or activating carbonaceous material
This disclosure relates to carbonizing and activating carbonaceous material. In some embodiments, the material is selected from coconut-derived material and like material of vegetable origin and resin materials to produce activated carbon, the production comprising supplying the material to the inlet end of a kiln, supplying to the kiln an atmosphere comprising steam or carbon dioxide substantially free of oxygen, maintaining a first region of the kiln having an independently controllable supply of heat at a temperature sufficient for drying or removing solvent from the material without carbonization, maintaining a second region of the kiln having an independently controllable supply of heat downstream from the first region at a temperature sufficient for carbonization of the material without activation; maintaining a third region of the kiln having an independently controllable supply of heat downstream from the second region at a temperature sufficient for activation of the carbonized material, and collecting activated carbon from the discharge end of the kiln.
1. A process for carbonizing and activating carbonaceous material selected from the group consisting of coconut-derived material and like material of vegetable origin and resin materials to produce activated carbon, said process comprising:
providing an externally fired rotary kiln having:
inlet and discharge ends,
a downward slope towards its discharge end,
annular weirs at intervals along the kiln for controlling progress of the material and
lift bars between the weirs for agitating the material, lifting portions of the material, and causing lifted material to cascade to the bottom of the rotary body, each annular weir retaining behind it a body of material to be treated, and progress of the material being primarily overflow as additional material is supplied; the process comprising:
supplying the material to the inlet end of the kiln;
supplying to the kiln an atmosphere comprising steam or carbon dioxide substantially free of oxygen;
maintaining a first region of the kiln having an independently controllable supply of heat at a temperature sufficient for drying or removing solvent from the material without carbonization;
maintaining a second region of the kiln having an independently controllable supply of heat downstream from the first region at a temperature sufficient for carbonization of the material without activation;
maintaining a third region of the kiln having an independently controllable supply of heat downstream from the second region at a temperature sufficient for activation of the carbonized material; and
collecting activated carbon from the discharge end of the kiln.
2. The process of claim 1 , further comprising maintaining a fourth region of the kiln having an independently controllable supply of heat downstream of the third region at a temperature such that the carbonized and activated material cools before reaching the discharge end of the kiln.
3. The process of claim 1 ,
wherein the carbonaceous materials selected is resin material is in the form of beads.
4. The process of claim 3 ,
wherein the beads are mesoporous beads and the activated carbon product has macropores, mesopores and micropores.
5. The process of claim 4 ,
wherein the beads are of phenolic resin.
6. The process of claim 5 ,
wherein the beads are the result of curing in phenolic resin in a pore-forming solvent.
7. The process of claim 1 ,
wherein the kiln is provided with 5-10 weirs along its length.
8. The process of claim 1 ,
wherein superheated steam is introduced at the discharge end of the kiln and flows counter-current to the material to provide the furnace atmosphere.
9. The process of claim 8 ,
wherein the steam is introduced at about 150° C.
10. The process of claim 1 ,
wherein the rate of feed of the material provides a residence time for the material of 2-5 hours.
11. The process of claim 1 ,
wherein the maximum bed depth adjacent each weir is about 10 cm.