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Method for simultaneous use of a single additive for coal flotation, dewatering, and reconstitution

  • US 5,379,902 A
  • Filed: 11/09/1993
  • Issued: 01/10/1995
  • Est. Priority Date: 11/09/1993
  • Status: Expired due to Term
First Claim
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1. A method for floating, dewatering and reconstituting fine coal comprising:

  • a) combining the fine coal with water in a first predetermined proportion so as to formulate a slurry;

    b) mixing the aqueous slurry with a single addition of heavy oil phase emulsion in a second predetermined proportion and at a first predetermined mixing speed and for a predetermined period of time so as to form a coal-emulsion mixture, wherein said heavy oil emulsion is formed by mixing a first surfactant with a heavy oil and then mixing into said heavy oil-first surfactant mixture a water-second surfactant mixture, wherein said heavy oil is selected from the group consisting of aliphatic bitumen, highly aromatic coal tars, tar sand-derived bitumen, oil shale-derived bitumen, gilsonite, and combinations thereof, said first surfactant is selected from the group consisting of linear polyoxyethylene alkoxides, nonylphenol alkoxides, hydroflurorcarbon alkoxides, anionic fatty acid surfactants, cationic fatty amine emulsifiers and combinations thereof, said second surfactants is selected from the group consisting of fluorosurfactants, straight chain surfactants and combinations thereof, wherein said weight ratio of the constituents of the heavy oil emulsion is 30-60 percent heavy oil, 0.5-10 percent first surfactant, 15-35 percent water and 0.01-2 percent second surfactant;

    c) subjecting the coal-emulsion mixture to forth flotation, thereby forming floating clean coal fraction in the form of a froth and a tailing containing mineral matter;

    d) dewatering the froth to produce dewatered clean, agglomerated coal; and

    e) drying the dewatered clean coal to form a reconstituted dust-less product.

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