Patent GB-761021-A (GB)
Title: Separation of solids from aqueous suspension
IPC: C09K23/52
Filed: 1954-10-22
Abstract: In the method for concentrating and separating finely divided solids from aqueous suspension by admixing with the suspension an acrylamide polymer, the polymer is admixed in the form of an aqueous solution containing not more than 0.5 per cent by weight of the polymer and thereafter maintaining the suspension under conditions of minimal agitation until the desired separation is complete.  The preferred concentration of the polymer solution is from 0.00025 to 0.1 per cent by weight.  The amount used is preferably that sufficient to accomplish the flocculation and sedimentation of the solids and after the minimal agitation stage the suspension is sedimented or filtered. In the former case the layer, in the sedimentation vessel used which is concentrated with respect to solids, is subjected to mild mechanical working to accomplish a further concentration.  The preferred polymers are water-soluble, have high molecular weight, are free from cross linking and have a specified viscosity.  There may be used the homopolymer of acrylamide and copolymers of acrylamide with up to 15 per cent by weight of monomers such as acrylic acid, alkyl esters of acryl acid and methacrylic acid, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl alkyl ethers and vinyl and vinylidene chloride.  Not more than 15 per cent of the amide groups should be replaced by carboxyl groups.  Whichever addition method is adopted, violent agitation during it should be avoided.  In the first method the solution may be sprayed into a flume, equipped with baffles or slow agitators, through which the suspension is moving, or the solution and suspension may be pumped together into a mixing chamber designed to utilize the momentum of the liquids to accomplish thorough and gentle mixing.  Reference has been directed by the Comptroller to Specification 725,460.ALSO:In the method for concentrating and separating finely-divided solids from aqueous suspension by admixing with the suspension an acrylamide polymer, the polymer is admixed in the form of an aqueous solution containing not more than 0,5 per cent by weight of the polymer and thereafter maintaining the suspension under conditions of minimal agitation until the desired separation is complete.  The preferred concentration of the polymer solution is from 0,00025 to 0,1 per cent by weight.  The amount used is preferably that sufficient to accomplish the flocculation and sedimentation of the solids and after the minimal agitation stage the suspension is sedimented or filtered. In the former case the layer, in the sedimentation vessel used, which is concentrated with respect to solids, is subjected to mild mechanical working to accomplish a further concentration.  The preferred polymers are water-soluble, have high molecular weight, are free from cross linking and have a specified viscosity.  There may be used the homopolymer of acrylamide and copolymers of acrylamide with up to 15 per cent by weight of monomers such as acrylic acid, alkyl esters of acryl acid and methacrylic acid, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl alkyl ethers and vinyl and vinylidene chloride.  Nor more than 15 per cent of the amide groups should be replaced by carboxyl groups.  Whichever addition method is adopted, violent agitation during it should be avoided.  In the first method the solution may be sprayed into a flume, equipped with baffles or slow agitators, through which the suspension is moving, or the solution and suspension may be pumped together into a mixing chamber designed to utilize the momentum of the liquids to accomplish thorough and gentle mixing.  Reference has been directed by the Comptroller to Specification 725,460.ALSO:In the method for concentrating and separating finely-divided minerals from aqueous suspension by admixing with the suspension an acrylamide polymer, the polymer is admixed in the form of an aqueous solution containing not more than 0.5 per cent by weight of the polymer and thereafter maintaining the suspension under conditions of minimal agitation until the desired separation is complete.  The preferred concentration of the polymer solution is from 0.00025 to 0.1 per cent by weight.  The amount used is preferably that sufficient to accomplish the flocculation and sedimentation of the solids and after the minimal agitation stage the suspension is sedimented or filtered. In the former case the layer, in the sedimentation vessel used, which is concentrated with respect to solids, is subjected to mild mechanical working to accomplish a further concentration.  The preferred polymers are water-soluble, have high molecular weight, are free from cross linking and have a specified viscosity.  There may be used the homopolymer of acrylamide and copolymers of acrylamide with up to 15 per cent by weight of monomers such as acrylic acid, alkyl esters of acryl acid and methacrylic acid, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl alkyl ethers and vinyl and vinylidene chloride.  Not more than 15 per cent of the amide groups should be replaced by carboxyl groups.  Whichever addition method is adopted, violent agitation during it should be avoided.  In the first method the solution may be sprayed into a flume, equipped with baffles or slow agitators, through which the suspension is moving, or the solution and suspension may be pumped together into a mixing chamber designed to utilize the momentum of the liquids to accomplish thorough and gentle mixing.  Reference has been directed by the Comptroller to Specification 725,460.