Flocculation of coal fines with polyelectrolytes and electrolyte
AssigneeBetz Laboraties, Inc.
InventorsStephen R. Vasconcellos, Phuong-Thao Luong
Life of this patent
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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.
Claims23
A process for the flocculation of coal fines in water which comprises
- (a) adding a cationic polyelectrolyte to a suspension of coal fines in water;
- (b) adding at least about 4ppm CaC1.sub.2 to the suspension;
- (c) adding an anionic polyelectrolyte to the suspension;
- and
- (d) separating the flocculated coal fines from the aqueous suspension;
- the anionic polyelectrolyte being selected from the group consisting of an acrylic acid/acrylamide copolymer and a terpolymer of acrylic acid, methacrylic acid, and ethylacrylate;
- the cationic polyelectrolyte being selected from the group consisting of a dimethylamino methylmethacrylate methyl chloride quaternary ammonium salt/acrylamide copolymer, and N, N dimethyl 2 hydroxy propyl imine homopolymer, a diallyl dimethyl ammonium chloride polymer, a ter polyepichlorohydrin dimethyl amine polymer;
- the CaC1.sub.2, cationic polyelectrolyte, and anionic polyelectrolyte being added in amounts and in a sequence effective to flocculate the coal fines, wherein said cationic polyelectrolyte is added prior to the addition of said anionic polyelectrolyte.
A process for the flocculation of coal fines suspended in water which comprises
- (a) an anionic adding polyelectrolyte to a suspension of coal fines in water;
- (b) adding at least about 200 ppm CaC1.sub.2 to the suspension;
- (c) adding a cationic polyelectrolyte to the suspension which second polyelectrolyte is an anionic polyelectrolyte where a cationic polyelectrolyte was added in step a, and a cationic polyelectrolyte where an anionic polyelectrolyte was added in;
- and
- (d) separating the flocculated coal fines from the aqueous suspension;
- the anionic polyelectrolyte being selected from the group consisting of an acrylic acid/acrylamide copolymer and a terpolymer of acrylic acid, methacrylic acid and ethylacrylate;
- the cationic polyelectrolyte being selected from the group consisting of a dimethylamino methylmethacrylate methyl chloride quaternary ammonium salt/acrylamide copolymer, an N,N, dimethyl 2 hydroxy propyl imine homopolymer, a diallyl dimethyl ammonium chloride polymer, and a ter polyepichlorohydrin dimethyl amine polymer;
- the CaC1.sub.2, anionic polyelectrolyte and cationic polyelectrolyte being added in amounts and in a sequence effective to flocculate the coal fines, wherein said anionic polyelectrolyte is added prior to said cationic polyelectrolyte.
The process of claim, 5 wherein the coal fines are of coal having a surface charge about equal to or greater than that of lignite.
A process for the flocculation of coal fines suspended in water, which coal fines comprise coal having a surface charge about equal to or greater than that of lignite which comprises
- (a) adding an acrylic acid/acrylamide copolymer to the suspension of the coal fines in water;
- (b) adding at least about 200 ppm CaC1.sub.2 to the suspension;
- (c) adding an N,N, dimethyl 2 hydroxy propyl imine homopolymer formula to the suspension;
- and
- (d) separating the flocculated coal fines from the aqueous suspension;
- wherein the acrylic acid/acrylamide copolymer, CaC1.sub.2, and the N,N dimethyl 2 hydroxy propyl imine homopolymer are added in amounts and in a sequence effective to flocculate the coal fines, and wherein said copolymer is added prior to said homopolymer.
A process for the flocculation of coal fines suspended in water, which coal fines comprise coal having a surface charge about equal to or greater than that of lignite, which comprises
- (a) adding a terpolymer of acrylic acid, methacrylic acid and ethylacrylate to the suspension of the coal fines in water;
- (b) adding at least about 200 ppm CaC1.sub.2 to the suspension;
- (c) adding a dimethylamino methylmethacrylate methyl chloride quaternary ammonium salt/acrylamide copolymer to the suspension;
- and
- (d) separating the flocculated coal fines from the aqueous suspension;
- wherein the terpolymer, the CaC1.sub.2, and the dimethylamino methylmethacrylate methyl chloride quaternary ammonium salt/acrylamide copolymer are added in amounts and in a sequence effective to flocculate the coal fines, and wherein said terpolymer is added prior to said copolymer.
A process for the flocculation of coal fines suspended in water, which coal fines comprise coal having a surface charge about equal to or less than that of anthracite, which comprises
- (a) adding a diallyl dimethyl ammonium chloride polymer to the suspension of the coal fines in water;
- (b) adding at least about 4 ppm CaC1.sub.2 to the suspension;
- (c) adding an acrylic acid/acrylamide copolymer to the suspension;
- and
- (d) separating the flocculated coal fines from the aqueous suspension;
- wherein the diallyl dimethyl ammonium chloride polymer, CaC1.sub.2, and the acrylic acid/acrylamide copolymer are added in amounts and in a sequence effective to flocculate the coal fines, and wherein said polymer is added prior to said copolymer.
Dependencies are inferred from the claim text.