Patents Assigned to Betz Laboraties, Inc.
  • Patent number: 4906386
    Abstract: Coal fines are flocculated from an aqueous suspension by adding an anionic polyelectrolyte, a soluble calcium salt, and a cationic polyelectrolyte to the suspension. The anionic polyelectrolyte is preferably a high charge density, high molecular weight acrylic acid/acrylamide copolymer or a high charge density high molecular weight terpolymer of acrylic acid/methacrylic acid/ethylacrylate. The cationic polyelectrolyte is preferably a high molecular weight, low charge density dimethylamino methylmethacrylate methyl chloride quaternary ammonium salt/acrylamide copolymer, an N,N dimethyl 2 hydroxy propyl imine homopolymer or low molecular weight, a diallyl dimethyl ammonium chloride polymer, or ter polyepichlorohydrin dimethyl amine.
    Type: Grant
    Filed: November 3, 1988
    Date of Patent: March 6, 1990
    Assignee: Betz Laboraties, Inc.
    Inventors: Stephen R. Vasconcellos, Phuong-Thao Luong