Method for carbonizing lignocelluosic material as a powder
The present invention provides a novel cost efficient method for carbonizing lignocellulosic material to carbonized particles or agglomerates, preferably carbon powder. Also uses of said particles or agglomerates are disclosed.
1. A method for manufacturing carbonized particles or agglomerates, comprising the following steps:
a) providing a dried raw material in powder form emanating from a ligno-cellulosic material,
b) suspending said raw material in an inert gas medium to form a powder-gas suspension,
c) continuously conveying the powder-gas suspension into, through and out of a hot chamber and continuously treating said raw material in the powder-gas suspension during a time period from about one millisecond up to about a quarter of an hour at a temperature range of from about 900 to about 1800° C., thus providing one or more carbonized particles or agglomerates,
d) cooling the carbonized particles or agglomerates, and
e) separating carbonized particles or agglomerates from off-gases or other residues.
2. The method according to claim 1 wherein the inert gas medium comprises a mixture of nitrogen and carbon-dioxide.
3. The method according to claim 1 wherein the raw material of step a) is above 90% dry solids.
4. A method according to claim 1 wherein the raw material in step a) has been pre-treated.
5. The method according to claim 1 wherein the raw material of step a) has been milled to a defined particle size, involving also treatment with aiding agents, wherein the adding agents are impregnation with a liquid, solvent, salt, water, or a mixture thereof.
6. The method according to claim 1 , further comprising,
f) a post treatment step.
7. The method according to claim 6 wherein the post-treatment of step f) includes milling, impregnating and/or coating of said carbonized particles or agglomerates to defined particle size, surface properties, surface polarization and/or affinity for certain substances.
8. A method according to claim 1 yielding carbonized particles or agglomerates having a BET surface area of above 100 m 2 /g.
9. A method according to claim 8 wherein the carbonized particles or carbonized agglomerates therein exhibit dimensions from about 1 nm to about 1 mm.
10. The method according to claim 1 , wherein said carbonized particles or agglomerates are in the form of a carbon powder.
11. The method according to claim 1 , wherein said carbonized particles or agglomerates are in the form of an electrically conductive carbon powder.
12. The method according to claim 1 , wherein the ligno-cellulosic material of step a) is lignin.
13. The method according to claim 1 , wherein the carbonization of the raw material in step c) is at a temperature range from about 1000 to about 1400° C.
14. A method according to claim 6 wherein the separation step e) involves extraction and/or collection, from the inert gas medium before step f) post-treatment.
15. The method according to claim 1 , wherein the hot chamber is a furnace system.
16. The method according to claim 7 , wherein the carbonized particles or agglomerates are in the form of a carbon powder.
17. A method according to claim 1 yielding carbonized particles or agglomerates having a BET surface area from about 130 to about 1000 m 2 /g.
18. A method according to claim 8 wherein the carbonized particles or carbonized agglomerates therein exhibit dimensions from about 10 nm to about 500 μm.
19. A method according to claim 8 wherein the carbonized particles or carbonized agglomerates therein exhibit dimensions from about 10 nm to about 250 μm.
20. A method according to claim 4 wherein, in the raw material pretreatment in step a), the raw material is homogenized, milled, crushed and/or impregnated with a fluidic medium.
21. A method according to claim 1 wherein the raw material powder-gas suspension is conveyed through the hot chamber in a controlled vortex flow.
22. A method according to claim 1 further comprising controlling the powder-gas suspension during the step of conveying through the hot chamber so that the powder has little or no contact time with walls of the hot chamber.
23. The method according to claim 1 wherein the inert gas medium is nitrogen.
24. A method for manufacturing carbonized particles or agglomerates, comprising the following steps:
a) providing a dried raw material in powder form emanating from a ligno-cellulosic material,
b) suspending said raw material in an inert gas medium to form a powder-gas suspension, wherein the raw material powder is suspended in the inert gas medium by thermal spraying,
c) continuously conveying the powder-gas suspension into and through a hot chamber and continuously treating said raw material in the powder-gas suspension during a time period from about one millisecond up to about a quarter of an hour at a temperature range of from about 900 to about 1800° C., thus providing one or more carbonized particles or agglomerates,
d) cooling the carbonized particles or agglomerates, and
e) separating carbonized particles or agglomerates from off-gases or other residues.