Method for concentrating the exinite group macerals from coal by froth flotation

A method for separating coal and a resin concentrate from an aqueous slurry containing resin solids, finely divided coal solids and finely divided inorganic solids, said method consisting essentially of:

• (a) adjusting the concentration of said slurry to from about 3 to about 15 weight percent solids;
• (b) admixing from about 25 to about 50 mg of a first froth flotation agent selected from the group consisting of short chain alcohol frothing agents containing from about 6 to 8 carbon atoms and from about 2 to about 10 mg of a second froth flotation agent selected from the group consisting of polyglycol-type frothers per kilogram of said solids in said slurry with said slurry to produce a mixture;
• (c) admixing an additional quantity of from about 25 to about 50 mg of said first froth flotation agent per kilogram of said solids in said slurry with said mixture in a first froth flotation zone at an average residence time from about 3 to about 6 minutes after charging said mixture to said first froth flotation zone;
• (d) subjecting said mixture to froth flotation in said first froth flotation zone for a total average residence time from about 8 to about 10 minutes to produce a resin and coal-rich stream and an inorganic solids rich stream;
• (e) admixing up to about 5 mg of said first froth flotation agent per kilogram of said solids in said slurry with said resin and coal-rich stream to produce a second mixture;
• (f) subjecting said second mixture to froth flotation in a second froth flotation zone for an average residence time from about 3 to about 6 minutes to produce a resin-rich stream and a first coal-rich stream;
• (g) admixing up to about 5 mg of said first froth flotation agent per kilogram of said solids in said slurry with said resin-rich stream to produce a third mixture;
• (h) subjecting said third mixture to froth flotation in a third froth flotation zone for an average residence time from about 1 to about 4 minutes to produce a resin concentrate stream and a second coal-rich stream;
• (i) recycling said second coal-rich stream to said second froth flotation zone;
• and
• (j) producing a particulate resin concentrate from said resin concentrate stream.