# US 9,751,110 B2 · Method for the classification of water absorbent polymer particles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,751,110 B2 - Document ID: US9751110B2 - Status: Granted - Kind: B2 - Application number: 12/438,481 - Filed: 2007-09-24 - Published: 2009-10-22 - Granted: 2017-09-05 - Earliest claimed: 2006-09-25 - Assignees: BASF SE - Applicants: Uwe Stueven; Rüdiger Funk; Matthias Weismantel; Meinhard Nitschke; Filip Mees; Leo Van Miert - Inventors: Uwe Stueven; Rüdiger Funk; Matthias Weismantel; Meinhard Nitschke; Filip Mees; Leo Van Miert - Web page: https://patentgrep.com/patent/US9751110B2 ## CPC - B07B 1/28: Moving screens not otherwise provided for, e.g. swinging, reciprocating, rocking, tilting or wobbling screens - B07B 1/00: Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like {(ash-sifters for domestic stoves or ranges F24B15/007)} - B07B 13/16: Feed or discharge arrangements - B07B: SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL (wet separating processes, sorting by processes using fluent material in the same way as liquid B03; combinations of dry separating apparatus with wet separating apparatus B03B; using liquids B03B, B03D; sorting by magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high voltage electric fields B03C; centrifuges or vortex apparatus for carrying out physical processes B04; hand sorting, postal sorting, sorting by switching or other devices actuated in response to detection or measurement of some feature of articles or samples of material B07C) ## Abstract A process for continuously classifying water-absorbing polymer beads by means of at least one screen, at least one screen having at least one guide device on the screen surface. ## Claims ### Claim 1 A process for continuously classifying dried water-absorbing polymer beads comprising deflecting dried polymer beads moving toward a screen at least partly from an original direction of movement to the middle of the screen by at least one first guide device on the screen surface, and guiding the polymer beads in a spiral path toward an exit orifice at the edge of the screen by a second guide device, wherein the water-absorbing polymer beads, during the classification, have a water content below 15 wt % and have a temperature of at least 40° C. ### Claim 2 (depends on 1) The process according to claim 1, wherein the guide device has a height of from 1 to 10 cm relative to the screen surface. ### Claim 3 (depends on 1) The process according to claim 1, wherein the at least one guide device concludes flush to the edge of the screen at one end. ### Claim 4 (depends on 1) The process according to claim 1, wherein a tumbling screen machine is used. ### Claim 5 (depends on 4) The process according to claim 4, wherein the tumbling screen machine has at least two screens. ### Claim 6 (depends on 5) The process according to claim 5, wherein the tumbling screen machine, between the at least two screens, has a device for deflecting the polymer beads falling down from an upper screen in the direction of a middle of a lower screen. ### Claim 7 (depends on 1) The process according to claim 1, wherein the first guide device directing the polymer beads toward the middle of the screen is directed by at least 1%, based on screen radius, toward the middle of the screen. ### Claim 8 (depends on 1) The process according to claim 1, wherein the first guide device directing the polymer beads toward the middle of the screen is straight. ### Claim 9 (depends on 1) The process according to claim 1, wherein the first guide device directing the polymer beads toward the middle of the screen has a length of from 5 to 20% based on screen radius. ### Claim 10 (depends on 1) The process according to claim 1, wherein the second guide device which guides the polymer beads in a spiral path toward the exit orifice of the screen comprises a circular segment of at least 180° concentric about the screen center. ### Claim 11 (depends on 10) The process according to claim 10, wherein the circular segment concentric about the screen center has a diameter of at least 50% based on the screen diameter. ### Claim 12 (depends on 1) The process according to claim 1, wherein all screens have at least one first guide device. ### Claim 13 (depends on 1) The process according to claim 1, wherein at least one screen has a mesh width in the range from 100 to 1000 μm. ### Claim 14 (depends on 1) The process according to claim 1, wherein the classification is effected under reduced pressure. ### Claim 15 (depends on 1) The process according to claim 1, wherein a throughput per hour of water-absorbing polymer beads in the course of classification is at least 100 kg per m2 of screen area. ### Claim 16 (depends on 1) The process according to claim 1, wherein the water-absorbing polymer beads are flowed over by a gas stream during the classification. ### Claim 17 (depends on 16) The process according to claim 16, wherein the gas stream has a temperature of from 40 to 120° C. ### Claim 18 (depends on 16) The process according to claim 16, wherein the gas stream has a steam content of less than 5 g/kg. ### Claim 19 (depends on 1) The process according to claim 1, wherein the water-absorbing polymer beads comprise at least partly neutralized polymerized acrylic acid to an extent of at least 50 mol %. ### Claim 20 (depends on 1) The process according to claim 1, wherein the water-absorbing polymer beads have a centrifuge retention capacity of at least 15 g/g.