Deinking of paper using magnetic forces
OwnerDavid Malcolm Oweninventor
Life of this patent
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Abstract
A method for removal of magnetic ink from pulp stock formed from xerographic and laser printed paper waste comprising feeding such pulped paper waste past one or more magnets for removal of all or substantially all of such magnetic ink. The magnetic ink can be removed by capture or deflection techniques. The preferred pulp slurry has a concentration of 4% or less by weight pulp. The preferred magnetic force to be applied utilizes background magnetic fields in excess of 2000 Gauss and a field gradient in excess of 500 Gauss/cm. Also, a method for improving the recyclability of paper waste having ink thereon which does not normally contain a magnetic component, by utilizing one or more magnetic carriers in the formulations of the printing ink utilized.
Claims17
A method of separating laser and xerographic ink from paper pulped comprising;
- forming a pulp slurry having a pulp concentration of 4% or less by weight containing paper which has been printed with an ink containing a magnetizable ink;
- passing the slurry by a magnetic force sufficient to pull magnetizable particles out of the slurry;
- and wherein the magnetic force utilized is a magnetic field in excess of 2,000 Gauss or more and a field gradient of 500 Gauss/em or more.
The process of 1 wherein the pulp concentration is 0.75% by weight or less.
A method of removing ink with a magnetizable component comprising:
- (a) forming a slurry of pulped paper which had been printed by magnetizable ink having a concentration of 1% or less of pulp by weight;
- (b) subjecting the slurry to a magnetic force of 1.times.10.sup.6 Gauss 2/cm or more to pull the magnetizable ink towards the magnetic force;
- (c) removing the slurry from the magnetic force so that magnetizable ink particles in the slurry are separated from the pulp slurry.
A method of separating laser and xerographic ink from paper consisting essentially of:
- (a) pulping paper which has been printed with laser or xerographic ink in water to form a slurry having a pulp concentration of 4% or less by weight;
- and
- (b) passing the slurry by a magnetic force having a magnetic field of at least 4000 Gauss and a field gradient of at least 1000 Gauss/era to remove magnetizable particles.
Dependencies are inferred from the claim text.