Fused calcined petroleum coke and method of formation

• US 6,039,791 A
• Filed: 10/23/1997
• Issued: 03/21/2000
• Est. Priority Date: 10/23/1997
• Status: Expired due to Term

• Current Assignee: Alcoa USA Corp. (Alcoa Corp.)
• Original Assignee: Alumax Incorporated (Alcoa Corp.)
• Inventors: Perruchoud, Raymond, Kazeef, Michael G.
• Primary Examiner(s): Yildirim, Bekir L.
• Application Number:
  US08/956,543
• Time in Patent Office: 880 Days
• Field of Search: 208/131, 75/764, 75/766, 201/25
• US Class Current: 75/764
• CPC Class Codes: C10L 9/08 by heat treatments, e.g. calcining
• CPC Class Codes: C25C 3/06 of aluminium

Abstract

Certain physical properties, chemical composition and a content of volatile carbonaceous materials define the limits of the use of coke by-products of crude oil refining as green cokes for use in the manufacture of calcined cokes suitable in the production of anodes for the reduction processes in the aluminum industry. These limits render large quantities of green coke unusable for the purpose set forth above. The invention shows a way to overcome these limits by rendering up to now unusable cokes usable as green cokes for the manufacture of calcined cokes for the production of anodes.

Claims

1. A process for the production of anode grade coke comprised of the following steps:

(a) providing at least one granular green coke material to be calcined, said granular green coke material having a volatile carbonaceous materials content of greater than or equal to 16% by weight;

(b) positioning said at least one green coke material in a furnace; and

(c) heating said at least one green coke material in the furnace in the absence of air, under static conditions and controlled temperature and time, so as to reduce the volatile carbonaceous materials content and agglomerate of said granular green coke material to an anode grade homogeneous coke product having a Real density (kg/dm3) within an accepted range of 1.95-2.10 and a grain stability (%) (8-4 mm) of 60-95.

2. A process according to claim 1 which includes the step of heating said at least one granular green coke material to a temperature of between approximately 1000°

C. to 1200°

C.

3. A process according to claim 2 which includes the step of heating said at least one granular green coke material to temperature at a temperature gradient of between approximately 120°

C. per hour to approximately 240°

C. per hour.

4. A process according to claim 2 which includes the step of heating said at least one granular green coke material to temperature at a temperature gradient of between approximately 190°

C. per hour to approximately 210°

C. per hour.

5. A process according to claim 2 which includes the step of heating said at least one granular green coke material for a time period of between approximately 18 hours to approximately 34 hours.

6. A process according to claim 2 which includes the step of heating said at least one granular green coke material for a time period of between approximately 23 hours to approximately 25 hours.

7. A process according to claim 1 which includes the steps of heating said at least one green coke material wherein the core of the material reaches a temperature of between approximately 1000°

C. to approximately 1200°

C. and thereafter maintaining said at least one green coke material at said temperature for a period of between approximately 3.5 hours to approximately 5.5 hours.

8. A process according to claim 1 which includes the steps of heating said at least one green coke material wherein the core of the material reaches a temperature of between approximately 1000°

C. to 1200°

C. and thereafter maintaining said at least one green coke material at said temperature for a period of between approximately 3.8 hours to approximately 4.0 hours.

9. A process according to claim 1 which includes the step of processing said at least one granular green coke material prior to heating in order to obtain green coke material wherein between approximately 75 to approximately 85% wt. of the green coke material has a grain size of less than or equal to 2 mm.

10. A process according to claim 1 which includes the step of processing said at least one granular green coke material prior to heating in order to obtain a green coke material wherein between approximately 78 to approximately 81% wt. of the green coke material has a grain size of less than or equal to 2 mm.

11. A process according to claim 9 wherein substantially all of the residual product has a grain size of between approximately 2 mm to approximately 4 mm.

12. A process according to claim 1 wherein said granular green coke material is agglomerated in step (c) so as to form grains of a size of between approximately 50 mm to approximately 100 mm.

13. A process according to claim 12 including the step of processing said agglomerated anode grade coke product so as to form an anode grade coke product wherein between 30 to 40% wt. of the product has a grain size of greater than or equal to 4 mm with a maximum grain size of 25 mm.

14. A process according to claim 1 which includes the step of providing a chamber furnace.

15. A process according to claim 1 which includes the step of providing a shaft furnace.

16. A process according to claim 3 which includes the steps of heating said at least one granular coke material wherein the core of the material reaches a temperature of at least approximately 1000°

C. and thereafter holding the temperature for a period of between approximately 3.5 to approximately 5.5 hours.

17. A process according to claim 1 which includes the steps of providing a plurality of granular green coke materials and selectively mixing said granular green coke materials in amounts to produce an anode grade coke product having the following properties:

space="preserve" listing-type="tabular">______________________________________ Property Accepted Range ______________________________________ Sulphur (%) 0.5-3.5 Vanadium (ppm) 30-400 Nickel (ppm) 40-300 Tapped bulk 0.76-0.88 density (kg/dm.sup.3) (1 to 2 mm grain size) Real density (kg/dm.sup.3) 1.95-2.10 Grain stability (%) 60-95 (8 - 4 mm). ______________________________________

18. Coke formed from a process comprised of the following steps of:

(a) providing at least one granular green coke material to be calcined, said granular green coke material having a volatile carbonaceous materials content of greater than or equal to 16% by weight;

(b) positioning said at least one green coke material in a furnace;

(c) heating said at least one green coke material in the furnace in the absence of air under static conditions and controlled temperature and time so as to reduce the volatile carbonaceous materials content and agglomerate said granular green coke material to an anode grade coke product having a Real density (kg/dm3) within an accepted range of 1.95-2.10 and a grain stability (%) (8-4 mm) of 60-95.