Charles E. Capes

Removal of pyrite from coal by conditioning with Thiobacillus ferrooxidans followed by oil agglomeration

Abstract A novel process that can reject as much as 90% of the pyrite from finely divided coal is described. Cells of Thiobacillus ferrooxidans are mixed with an aqueous slurry of the coal and the mixture is vigorously agitated for as little as 15 min. Pyrite is apparently rendered hydrophilic and is rejected with the tailings when the hydrophobic coal is recovered by oil agglomeration. The process is superior to bacteriological oxidation which requires several days to remove comparable amounts of pyrite from coal through conversion to sulphate. It is shown that the bacterial cells can be recovered after agglomeration and used to treat at least six successive batches of coal. The minimum contact time, the minimum inoculum size and the ultimate number of times that the bacteria can be recycled are related variables that could not be defined under the laboratory conditions used. It was found, however, that Thiobacillus ferrooxidans grown on rejected tailings supplemented with inexpensive mineral salts are at least as effective in the process as cells grown in synthetic medium.

The effect of particle size and pH on the removal of pyrite from coal by conditioning with bacteria followed by oil agglomeration

Abstract The removal of 90% of the pyrite from coal by bacterial conditioning followed by oil agglomeration is attainable in Minto coal only if it is ball milled in the laboratory to an average particle size of about 5 μm. In grinding to industrially practical sizes of about 8 to 10 μm, the maximum amount of pyrite removed was about 50%. The contribution of the bacterial conditioning step was highly dependent on the pH of the feed slurry. A positive effect of bacterial conditioning was greatest at pH 2. At pH 10, the presence of bacteria was detrimental to desulfurization by oil agglomeration. Bacterial conditioning does not involve pyrite oxidation by Thiobacillus ferrooxidane because the pH of a coal—water mixture was normally above pH 5 for best pyrite depression where these bacteria are physiologically inactive, and because conditioning was achieved equally well with cells of Thiobacillus acidophilus and Escherichia coli.

Treatment of crude petroleum/water emulsions by agglomeration methods using fine coal

Persistent crude petroleum-water emulsions are produced in the recovery and extraction of heavier oils, for example, in the hot water processing of surface mined oil sands and during in-situ methods such as steam- or water-flooding. Over the past few years, much attention has been directed to the oil agglomeration method as a means of recovering and upgrading fine coal in water suspensions. The work reported here concerns the use of crude petroleum from produced emulsions in the coal agglomeration process. Two problems are adddressed in this way. Not only is oil recovered and emulsions broken in the case of the produced emulsions, but the coal is also benificiated through the rejection of water and inorganic impurities because of the selectivity of the agglomeration technique. Laboratory-scale experiments are reported using three different samples of produced emulsion from western Canada and a fine coal from waste tailings of a coal preparation plant. Results of the experiments are considered from the poi...

MEASUREMENT OF PARTICLE SIZE DISTRIBUTION IN COAL OIL WATER FUELS BY FOUR METHODS

ABSTRACT Four methods were used to measure the solids particle size distribution in coal-ol1-water fuel. Both dry and wet screening were utilized for the coarser particles while four different instrumental methods were used to measure the finer particles in diluted liquid suspension. The wet stages of the analyses included both solvent-diluted organic suspensions and measurement after inversion to an aqueous system. Consistent differences in the absolute values of particle size were observed between the four procedures. Possible reasons for these differences are discussed.