GB760653A - Method of separating solids from aqueous suspensions - Google Patents

Abstract

An aqueous suspension of a finely-divided mineral has mixed with it an acrylamide polymer hydrolyte having a specified minimum viscosity and having from 0.8 to 10 per cent of its amide groups replaced by carboxyl groups, the addition being an amount sufficient to accomplish the flocculation and sedimentation of the suspended solids. The preferred reagents are the hydrolytes of the homopolymer of acrylamide, but hydrolytes of water-soluble copolymers of acrylamide with up to 15 per cent by weight of monomers such as alkyl esters of acrylic acid and methacrylic acid, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl alkyl ethers and vinyl and vinylidene chloride. The reagent is mixed with water and agitated vigorously, preferably at room temperature, and added to and dispersed through the suspension held in a tank, or introduced into a pipe conveying the suspension where mixing is accomplished by turbulent flow. Preferred solution concentrations lie in the range from 0.003 to 0.1 per cent by weight of reagent, but may be as high as 0.5 per cent. The solution is used in an amount of from 0.001 lbs. to 2 lbs. per short ton of suspended solids. The pH of the suspension should be adjusted to lie in the range 1 to 11.5, and its temperature maintained below 60 DEG C. Examples are given demonstrating improved filtration or settling rates. Reference has been directed by the Comptroller to Specification 725,460.ALSO:In a method for concentrating a finely divided solid mineral in an aqueous suspension and separating it from the suspension, there is mixed with the suspension an acrylamide polymer hydrolyte having a specified minimum viscosity and having from 0,8 to 10 per cent of its amide groups replaced by carboxyl groups, in an amount sufficient to accomplish the flocculation and sedimentation of the suspended solids. The preferred reagents are the hydrolytes of the homopolymer of acrylamide, but hydrolytes of water-soluble copolymers of acrylamide with up to 15 per cent by weight of monomers such as alkyl esters of acrylic acid and metha-crylic acid, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl alkyl ethers and vinyl and vinylidene chloride. The reagent is mixed with water and agitated vigorously, preferably at room temperature, and added to and dispersed through the suspension held in a tank, or introduced into a pipe conveying the suspension where mixing is accomplished by turbulent flow. Preferred solution concentrations lie in the range from 0,003 to 0,1 per cent by weight of reagent, but may be as high as 0,5 per cent. The solution is used in an amount of from 0,001 lbs. to 2 lbs. per short ton of suspended solids. The pH of the suspension should be adjusted to lie in the range 1 to 11,5 and its temperature maintained below 60 DEG C. Examples are given demonstrating improved filtration or settling rates. Reference has been directed by the Comptroller to Specification 725,460.ALSO:An aqueous suspension of a finely-divided mineral has mixed with it an acrylamide polymer hydrolyte having a specified minimum viscosity and having from 0.8 to 10 per cent of its amide groups replaced by carboxyl groups, the addition being an amount sufficient to accomplish the flocculation and sedimentation of the suspended solids. The preferred reagents are the hydrolytes of the homopolymer of acrylamide, but hydrolytes of water-soluble copolymers of acrylamide with up to 15 per cent by weight of monomers such as alkyl esters of acrylic acid, and methacrylic acid, methacrylamide, styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl alkyl ethers and vinyl and vinylidene chloride. The reagent is mixed with water and agitated vigorously, preferably at room temperature, and added to and dispersed through the suspension held in a tank, or introduced into a pipe conveying the suspension where mixing is accomplished by turbulent flow. Preferred solution concentrations lie in the range from 0.003 to 0.1 per cent by weight of reagent, but may be as high as 0.5 per cent. The solution is used in an amount of from 0.001 lbs. to 2 lbs. per short ton of suspended solids. The pH of the suspension should be adjusted to lie in the range 1 to 11.5 and its temperature maintained below 60 DEG C. Examples are given demonstrating improved filtration or settling rates. Reference has been directed by the Comptroller to Specification 725,460.