Coal Age

MAY 2018

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Page 33 of 51

32 May 2018 clean coal conversion continued oven batteries used around the world. These data are shown in Table 3. The coke-quality analytical results are similar to or exceed current foundry and blast furnace coke specifications. However, general acceptance of a new type of bri- quetted coke by a conservative steel indus- try must arise from its performance in actu- al commercial blast furnace tests. Since the Virginia carbonite plant can only produce 15,000-20,000 tons per year (tpy), to con- duct a blast furnace test would require on the order of 40,000 tons of coke briquettes to conduct one reliable test. It is for this limited reason that the Virginia carbonite plant has focused on making foundry-size coke initially because reliable tests in cupo- la furnace can be achieved with a thousand tons of coke or less. Future CTC plants are now being designed to produce thousands of tons of blast-furnace coke briquettes for the steel industry and foundry-size coke briquettes for the foundry industry. Conclusions The CTC Mild Gasification Process has been proven in two individual pilot plants; one pilot in Bristol, Virginia, during the 1990s and a second pilot plant at Nu- cor Steel's plant in Conway, Arkansas, in 2005-2006. Now a commercial demon- stration plant exists in Norton, Virginia, operating round the clock on a 24/7 hour schedule converting coal continuously into high-value carbon char and formed foundry-size coke briquettes. Any type and rank of coal can be con- verted into a carbon char by the removal and collection of the volatiles that are re- moved from the coal during the mild gas- ification coal conversion process operat- ing at a minimum of 500°C to a maximum level of 900°C when using an indirectly heated mild gasification reactor. However, the quality of the carbon char produced is directly related to the quality and type of coal being processed. The volatile level remaining in the car- bon char can be varied by the different op- erating conditions within the mild gasifi- cation reactor ranging from a volatile level as high as 14% to a volatile level as low as 2% depending upon the use of either a di- rectly heated or an indirectly heated mild gasification reactor. Numerous commercial markets exist for the high value, high-fixed-carbon char ranging from a smokeless fuel, to a carbon reductant in the mini-mill electric arc fur- naces, to a carbon absorbent for waste wa- ter and chemical treatment and recovery, to an activated carbon application and/or by further processing into coke briquettes for the foundry and steel industry. The carbon char made from both thermal type coals and metallurgical type coal can be further processed with various carbon additives into briquettes that can either be used in a non-calcined form or placed into a furnace for further calcina- tion into coke briquettes at a temperature ranging from 950°C to 1,100°C. The carbon char blended and pressed into coke briquettes can be made into var- ious shapes and sizes to meet the size and quality requirements of both the steel in- dustry and foundry industry. The first stage of the CTC Mild Gas- ification Process in the production of a carbon char also produces as a byproduct about one barrel of coal oil liquids per ton of coal processed plus sufficient synthetic non-condensable gases that can be used to heat the entire process as based upon the quality of coal processed. Naturally, the higher volatile coals will produce more coal oil liquids than lower volatile coals. The continuous mild gasification coke-making technology and process has a number of distinct advantages in the manufacturing of coke over the exist- ing coke oven batteries. A 1-million-tpy CTC continuous mild gasification coke making plant can be environmentally permitted in a quarter of the time re- quired to permit a coke battery primarily because the CTC process is a completely Table 2—Analytical quality of foundry-size coke briquettes produced at the Virginia Carbonite Plant. Coke Percentage Characteristics (%) 1. Moisture <1% 2. Ash 7.48% 3. Volatiles 0.76% 4. Fixed Carbon 90.76% 5. Sulfur 0.69% 6. Coke Density 1.2 gms/cm 3 7. Drop Shatter Index +96% Table 3—CTC briquetted coke compared to conventional coke made in coke-oven batteries. Physical Characteristics CTC Continuous Standard Coke % Briquetted Coke Specifications 1. CRI 24-31 32max 2. CSR 65-74 55min 3. Coke Stability 61-66 58 4. Coke Hardness 69 67 5. Moisture 2 max 5-7 6. Ash (dry basis) 7 8 7. Volatiles (dry basis) 0.5-1.0 1.0 max 8. Fixed Carbon (dry basis) 92 91 9. Sulfur (dry basis) 0.6 0.7 10. Bulk density 38 lb/ft 3 29 lb/ft 3 Figure 11—Coke briquettes made in CTC process of the quality for application in blast furnaces.

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