Abstract: The invention relates to a classification process for superabsorbent polymer particles, comprising classifying the water-absorbent polymer particles in a screen machine under reduced pressure wherein the pressure above the uppermost sieve is from 0 to 4.0 mbar per sieve higher than below the undermost sieve.

Abstract: The invention relates to a process for producing superabsorbent polymer particles, comprising surface postcrosslinking, classifying the surface postcrosslinked superabsorbent polymer particles, deagglomerating the separated oversize fraction using a roll crusher and recycling the disintegrated oversize fraction before or into the classification of the surface postcrosslinked superabsorbent polymer particles.

Abstract: A process for producing superabsorbents, comprising the steps of i) classifying the superabsorbent particles by means of one or more sieves and ii) removing metallic impurities by means of one or more magnetic separators, wherein classification is accomplished using sieves made of a wire mesh, the wires of the wire mesh consist of a steel composed of at least 70% by weight of iron, at least 10% by weight of chromium and less than 2.5% by weight of nickel, and the throughput of superabsorbent particles in the magnetic separator is in the range from 2.0 to 6.5 g/s per cm2 of free cross-sectional area.

Abstract: The invention relates to a process for producing superabsorbent polymer particles, comprising polymerization of a monomer solution, drying the resulting polymer gel and grinding the dried polymer gel with a roll mill, wherein the rolls of the roll mill are cleaned by reducing the feed rate to the roll mill, and if the deflection and/or the power consumption increases above a setpoint, operating the roll mill with reduced feed, and increasing the feed rate to the roll mill.

Abstract: The invention relates to a process for producing superabsorbent polymer particles, comprising storing acrylic acid in at least one tank (B1) at a production site for acrylic acid and in at least one tank (B2) at a production site for superabsorbent polymer particles, wherein the at least one tank (B1) at the production site for acrylic acid and the at least one tank (B2) at the production site for superabsorbent polymer particles are interconnected by one single pipe line (3) and the flow inside the pipe line (3) is temporary reversed during interruptions of the production superabsorbent polymer particles.

Abstract: The invention relates to a process for producing superabsorbent polymer particles, comprising polymerization of a monomer solution, wherein the monomer solution comprises partly neutralized acrylic acid formed by continuous mixing of acrylic acid and an aqueous solution of a base, the apparatus for preparing the partly neutralized acrylic acid comprises a vessel (B), and the feed line to vessel (B) ends inside vessel (B) below the liquid Level of the partly neutralized acrylic acid.

Abstract: The invention relates to a process for producing superabsorbent polymer particles, comprising polymerization of a monomer solution, wherein the monomer solution comprises partly neutralized acrylic acid formed by continuous mixing of acrylic acid and an aqueous solution of a base, the apparatus for preparing the partly neutralized acrylic acid comprises a vessel (B), and the vessel (B) has a cylindrical shape and a torispherical bottom.

Abstract: A process for producing superabsorbents, comprising the steps of i) classifying the superabsorbent particles by means of one or more sieves and ii) removing metallic impurities by means of one or more magnetic separators, wherein classification is accomplished using sieves made of a wire mesh, the wires of the wire mesh consist of a steel composed of at least 70% by weight of iron, at least 10% by weight of chromium and less than 2.5% by weight of nickel, and the throughput of superabsorbent particles in the magnetic separator is in the range from 2.0 to 6.5 g/s per cm2 of free cross-sectional area.

Abstract: The invention relates to a process for producing superabsorbent polymer particles, comprising surface postcrosslinking, classifying the surface postcrosslinked superabsorbent polymer particles, deagglomerating the separated oversize fraction using a roll crusher and recycling the disintegrated oversize fraction before or into the classification of the surface postcrosslinked superabsorbent polymer particles.

Abstract: The invention relates to a classification process for superabsorbent polymer particles, comprising classifying the water-absorbent polymer particles in a screen machine under reduced pressure wherein the pressure above the uppermost sieve is from 0 to 4.0 mbar per sieve higher than below the undermost sieve.

Abstract: Filling process for superabsorbent polymer particles The invention relates to a filling process for superabsorbent polymer particles, comprising discharging the superabsorbent polymer particles out of a silo into bulk container for shipping, wherein the filling level of the silo during filling of the bulk container is never less than 20%, in order to avoid particle segregation.

Abstract: Disclosed herein is a continuous process to make super absorbing polymer characterized by feeding at the head-end of a pressurized vessel, an aqueous solution of SAP forming monomer solution, either in un-neutralized or pre-neutralized condition, the monomer(s) being conveyed to the reactor vessel at a relatively low temperature of from 5° C. to 15° C. into a pressurized head feed zone of the reactor. The head pressure is maintained the reactor at a minimum level of greater than or equal to about 20 p.s.i.g. and the SAP advances to the discharge end. A relatively constant mass of SAP is maintained of at least 50% volume of SAP in the vessel, and the rate of entry and exit are kept relatively constant. The reaction vessel is equipped with a venting means to regulate the internal bead pressure to advance the SAP to the discharge end without mechanical agitation.