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US 9,803,033 B2Granted
Method for removing metal impurities
AssigneeBASF SE
InventorsRüdiger Funk, Jürgen Schröder, Thomas Pfeiffer, Emil Bitzer
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Abstract
A process for removing metallic impurities from a product mass flow comprising water-absorbing polymer particles by means of bar magnets, wherein the water-absorbing polymer particles comprise a surfactant and have direct contact with the bar magnets.
Claims12
A process for producing water-absorbing polymer particles by polymerizing a monomer solution or suspension comprising
- a) at least one ethylenically unsaturated monomer which bears an acid group and may be at least partly neutralized,
- b) at least one crosslinker,
- c) at least one initiator,
- d) optionally one or more ethylenically unsaturated monomer copolymerizable with the monomer specified under a), and
- e) optionally one or more water-soluble polymer,
- metallic impurities being removed from a product mass flow comprising water-absorbing polymer particles by a magnetic separator, the magnetic separator being formed from bar magnets, the bar magnets consisting of an austenitic steel sleeve and a magnetic material present within the sleeve, and the sleeve being bonded to the magnetic material in an undetachable manner, wherein the sleeves have direct contact to the water-absorbing polymer particles and the water-absorbing polymer particles comprise at least one surfactant,
- wherein the moisture content of the water-absorbing polymer particles is increased upstream of the magnetic separator.
4 more elements
A process for producing water-absorbing polymer particles by polymerizing a monomer solution or suspension comprising
- a) at least one ethylenically unsaturated monomer which bears an acid group and may be at least partly neutralized,
- b) at least one crosslinker,
- c) at least one initiator,
- d) optionally one or more ethylenically unsaturated monomer copolymerizable with the monomer specified under a), and
- e) optionally one or more water-soluble polymer,
- metallic impurities being removed from a product mass flow comprising water-absorbing polymer particles by a magnetic separator, the magnetic separator being formed from bar magnets, the bar magnets consisting of an austenitic steel sleeve and a magnetic material present within the sleeve, and the sleeve being bonded to the magnetic material in an undetachable manner, wherein the sleeves have direct contact to the water-absorbing polymer particles and the water-absorbing polymer particles comprise at least one surfactant,
- wherein an areal loading of the magnetic separator is 2 to 15 g/cm2s.
4 more elements
Dependencies are inferred from the claim text.