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Microbially Augmented Ash and Pyrite Physical Separation (MAAPPS) process R and D: Final technical report

Technical Report ·
OSTI ID:6788263

The goal of this project was to develop a novel mechanism to microbially enhance removal of ash and pyrite from coals during flotation. Studies were conducted to: 1) evaluate the attachment of Thiobacillus ferrooxidans to pyrite and ash; 2) optimize the growth of T. ferrooxidans on pyrite enriched process wastes; 3) optimize flotation of three coals with and without microbial pretreatment; 4) demonstrate continuous growth of T. ferrooxidans on tailings; and 5) evaluate cell-free media for pretreatment of coal to reject pyrite and/or ash during flotation. An additional task was undertaken to evaluate the use of T. ferrooxidans in comminution of coal for selective liberation of pyrite and ash. Attachment studies indicated that T. ferrooxidans may attach to pyrite particles, and chemical alteration of pyrite surfaces as well as agglomeration of the pyrite optimization studies indicated that several medium components may be reduced or eliminated when T. ferrooxidans is grown on pyrite tailings. Optimization of the column and froth flotation units resulted in nearly complete removal of liberated pyrite, thus limiting the potential for enhanced removal using microbes. Thus, only marginal selective depression of ash and pyrite occurred when pretreating the coal with T. ferrooxidans. T. ferrooxidans was successfully cultured in a continuous fermentor with production of consistent biomass density, using pyrite enriched tailings. Marginal enhancement of ash and pyrite rejection occurred when pretreating coal with cell-free culture filtrates. Treatment of coal with T. ferrooxidans over a period of days not only resulted in comminution but also in alteration of the characteristics of the coal mixture to achieve better mineral matter and sulfur rejection in some coals. 19 refs., 42 figs., 72 tabs.

Research Organization:
ARCTECH, Inc., Alexandria, VA (USA)
DOE Contract Number:
AC22-85PC81208
OSTI ID:
6788263
Report Number(s):
DOE/PC/81208-T3; ON: DE88009268
Country of Publication:
United States
Language:
English