1997 TMS Annual Meeting: Tuesday Session

CARBON TECHNOLOGY: Session I: Petroleum Coke

Session Chairperson: Lester Mc Coy, Great Lakes Carbon Corporation, P.O. Box "C", Port Arthur, TX 77640

8:30 am

CORRELATION OF COKE PROPERTIES, ANODE PROPERTIES, AND CARBON CONSUMPTION: C.T. Leach, D.G. Brooks, R.E. Gehlbach, Manufacturing Technology Laboratory, Reynolds Metals Company, 3326 East Second Street, Muscle Shoals, AL 35661-1258

Researchers often use calcined coke and anode core properties to predict carbon consumption in aluminum reduction cells. This study compared laboratory analysis data and production data from 1992 through 1995 at RMC's Lake Charles Carbon Company and Baie Comeau Reduction Plant. During this period, carbon plant operations produced anodes with a range of properties using various calcined cokes. The results indicate that calcined cokes having a relatively wide range of properties can produce quality prebake anodes that yield low, stable carbon consumptions. Some coke and anode properties that are considered important quality parameters had little or no detrimental effect on carbon consumption. Correlations exist between certain coke and anode properties during time periods where the properties changed significantly.

8:55 am

QUANTIFICATION OF THE INFLUENCE OF NICKEL ON REDUCTION CELL ANODES: Max Casada, Venco, P.O. Box 577, State Route 2, South Moundsville, WV 26041; Jeff Rolle, A.J. Edmond Co., 1530 West 16th Street, Long Beach, CA 90813; Chris Eppig, Dr. Steve Paspek, BP Oil Company, 4440 Warrensville Center Road, Cleveland, OH 44128-2837; Zeno DeMori, ORMET, P.O. Box 176/State Route 7, Hannibal, OH 43931; Gary Force, BP Oil Company, 200 Public Square, Cleveland, OH 44114; Jaime Mora, Juan Turpial, Venalum, CVG Industria Venezolana De Aluminio, C.A., Zona Industrial Matanzas, Estado Bolivar, Venezuela; David Hester, Conoco Inc., 1000 South Pine, Ponca City, OK 74602; Mirna Chirinos, Francisco Perez, Alcasa, CVG Aluminio Del Caroni S.A., Zona Industrial Matanzas, Estado Bolivar, Venezuela; Julio Velasco, Venco URB Villa Asia, Calle Bombay Manz. 27, #10, Puerto Ordaz, Bolivar, Venezuela; Eli Epstein, Don Pirolo, Venco, 600 N. Dairy Ashford, Houston, TX 77252

The concentration of various metallic compounds in crude oils and in the resulting petroleum coke has continued an upward trend as crude reserves continue to change and tend toward being increasingly heavy and sour. Traditionally labeled as a catalyst, nickel has been included with vanadium in the evaluation of its effects on anode reactivity. In 1995, a Task Force was formed to quantify the influence of nickel on reduction cell anodes as existing information in the literature did not address specifically the affects of varying concentrations of nickel on anodes. The task force prepared resid with identical properties with the exception of nickel content. These resids were then coked, calcined, and formed into anodes in as identical a process as possible. Finally, the anodes were baked and tested to determine the effects on their performance characteristics. The results and conclusions drawn from this process will be communicated in this paper.

9:20 am

VIBRATED BULK DENSITY (VBD) MEASUREMENT OF CALCINED COKE AND BINDER CONTROL IN PREBAKED ANODE PASTE : A CASE STUDY: Luc Duchesneau, Roland Lessard, André Gendron and Germain Brassard, Alcan International Limited, Arvida Research & Development Centre, 1955 Mellon Blvd, P.O. Box 1250, Jonquière, Québec, Canada G7S 4K8

Vibrated bulk density is used to establish the binder content in prebaked anode paste. Alcan adopted the calcined coke VBD analytical method from Collier Carbon in 1961 with slight modifications. Recent paste quality problems (sticking in baking furnaces) were associated with a lack of precision in the VBD. The apparatus was identified as the main cause of imprecision (irregular flow when feeding the cylinder with the vibrating spatula, increase of table vibration amplitude over time and cylinder holding system) and an improved semi-automatic version was constructed. This communication describes the critical parts of the apparatus and their impact on the quality of the results. It also discusses calibration approach, analytical performance achieved (a four-fold improvement in reproducibility sigma = 0.003) and the impact on the paste production control.

9:45 am

PETROLEUM COKE DEOILING FOR PROPERTIES DETERMINATION: R.E. Gehlbach, C.T. Leach, and V.A. Benoît, Reynolds Metals Co., 3326 E. Second Street, Muscle Shoals, AL 35661-1258

The presence of petroleum-based dedusting agents applied to calcined petroleum coke for control of fugitive dust precludes obtaining correct analytical results when certain tests are performed. Removal of various dedusting agents in commercial use is difficult and the process (es) employed may also affect the properties obtained. Results are presented for studies of thermal, solvent extraction, and vacuum deoiling methods and their effectiveness for several surface-sensitive tests. While all methods are observed to remove virtually all of the dedusting agents, different types of residues or decomposition products remain on the coke particles and adversely affect test results. Depending on the particular properties to be determined and the desired accuracy of the results, more than one technique may be required.

10:10 am BREAK

10:30 am

EFFECTS OF IRON AND SULPHUR ON THE AIR- AND CO2-REACTIVITY OF COKES: Trygve Eidet, Department of Electrochemistry, Norwegian Institute of Technology, Elkem ASA, Research, PO Box 8040 Vaagsbygd, N-4602 Kristiansand, Norway; Morten Sorlie, Elkem ASA, Research, PO Box 8040 Vaagsbygd, N-4602 Kristiansand, Norway; Jomar Thonstad, Department of Electrochemistry, Norwegian Institute of Technology, N-7034 Trondheim, Norway

The aim of this work was to investigate the effects of inorganic impurities on the reactivity of cokes and anode materials and at the same time to avoid the uncertainties that are introduced by the often complex background impurity content in industrial anode cokes. An aromatic distillate fraction from the production of coal tar pitch was used as coke precursor and cokes with controlled amounts of impurities were produced in a laboratory coker. Iron was added to the coke precursor as iron (III) acetylacetonate, and sulphur as dibenzothiophene. These organic substances dissolve in the precursor. The effects of iron and sulphur on the reactivities of cokes were measured in air at 500°C and in CO2 at 960°C. Surface studies (SEM, EDX) showed the topography of the surface, what iron phases were present and indicated the impact of iron and sulphur on the reaction.