Kinetics of the reduction of calcium sulfate with carbon monoxide and hydrogen

Technical Report · Thu Jul 01 04:00:00 EDT 1982

OSTI ID:6593993

Diaz-Bossio, L M

The reductive decomposition of calcium sulfate pellets with both hydrogen and carbon monoxide was studied experimentally in the range of 900 to 1100/sup 0/C. The conditions of the reaction were controlled in order to enhance the formation of calcium oxide while the production of the undesirable calcium sulfide was inhibited; carbon dioxide was used to prevent calcium sulfide formation. Cylindrical calcium sulfate pellets were prepared at a constant compression pressure and reduction was carried out initially at a constant temperature and various reductant gas concentrations. Additional experiments were made with a constant gas phase concentration and various reaction temperatures. Stabilization of the pellet through heating prior to initiating the reduction process was required in order to obtain reliable data. Treatment of the pellet at elevated temperatures caused sintering which reduced the pellet surface area to a value that changed little with additional heating time. Conversions of about 100% were obtained in several hours with both reductant gases at temperatures around 1000/sup 0/C and higher. The rate of calcium sulfate reduction with hydrogen was consistently found to be higher than that with carbon monoxide. The grain model was used to first determine the mechanism controlling the reduction process, then the grain shape factor was evaluated by fitting the data, and finally the parameters involved in the controlling mechanism were calculated. A first-order chemical reaction was found to be the predominant resistance limiting the rate of reduction. The highest correlation factors, around 0.99, were always obtained when a spherical grain shape factor was used in plotting the numerical solution of the governing equation. 42 figures, 3 tables.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6593993
• Report Number(s): IS-T-1007; ON: DE83004963
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CALCIUM SULFATES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CORRELATIONS
DATA
DECOMPOSITION
ELEMENTS
ENERGY
EXPERIMENTAL DATA
FABRICATION
GRAVIMETRIC ANALYSIS
HEAT TREATMENTS
HYDROGEN
INFORMATION
KINETICS
MOLDING
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PELLETIZING
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
REDUCTION
SPHERES
STABILIZATION
SULFATES
SULFUR COMPOUNDS
TEMPERATURE DEPENDENCE
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
VERY HIGH TEMPERATURE
YIELDS