Desulfurization of coal by microbiological leaching. Final report, September 1, 1978-June 1, 1980
The microbiological desulfurization of a high sulfur New Mexico (Carthage) coal has been investigated using an adapted strain of Thiobacillus ferrooxidans. Optimum conditions for this leaching were determined as: pH, 2.0; particle-size, -400 mesh (-37 ..mu..m); pulp density, 25%; and temperature, 35/sup 0/C. Under these conditions approximately 90% of the pyritic sulfur can be removed in 10 days from a coal sample containing 3.43% total sulfur of which 1.95% is pyritic. The rate of oxygen mass transfer into the leach suspensions was also measured and was shown to exceed that required for the oxidation of the pyrite by a factor of three. To study the feasibility of this approach on a semi-industrial scale, larger-scale tank leaching experiments were also conducted. Repeating this program of leaching for an Ohio coal as a basis for comparison produced the same optimum pH, particle size, and pulp density at 35/sup 0/C; and under these conditions 75% of the pyritic sulfur (about 5% of the sample weight) could be removed. The rate of oxygen mass transfer was also similar to the New Mexico coal experiments. From these results, a generalized flow sheet illustrating a possible scheme of pyrite leaching (removal) by the bacteria has been proposed. Finally, large pyrite cubes were cut and polished to expose the (100), (110), (111), and (112) crystal plane orientations. These regimes were separately leached under controlled conditions and it was observed that acid-ferric sulfate leaching is different from acid-bacterial leaching. In addition, leaching rates are different for the different crystal surface orientations.
- Research Organization:
- New Mexico Inst. of Mining and Technology, Socorro (USA). Dept. of Metallurgy
- OSTI ID:
- 6592436
- Report Number(s):
- NP-25377; EMD-2-67-3319
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COAL
DESULFURIZATION
PYRITE
LEACHING
BACTERIA
IRON SULFATES
REMOVAL
THIOBACILLUS FERROXIDANS
BACILLUS
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL REACTIONS
DISSOLUTION
ENERGY SOURCES
FOSSIL FUELS
FUELS
IRON COMPOUNDS
IRON SULFIDES
MATERIALS
MICROORGANISMS
MINERALS
ORES
OXYGEN COMPOUNDS
PYRITES
SEPARATION PROCESSES
SULFATES
SULFIDES
SULFUR COMPOUNDS
SULFUR ORES
TRANSITION ELEMENT COMPOUNDS
010402* - Coal
Lignite
& Peat- Purification & Upgrading