Magnetic separation method

Claim 1

A magnetic separation method which comprises the steps of: a) bringing a vessel having a bottom end and containing a liquid suspension of magnetically attractable particles into proximity with a magnet system, by effecting vertical movement of the magnet system relative to the vessel, whereby there is formed an annular or part-annular pellet comprising the magnetically attractable particles close to, but not at, the bottom of end of the vessel; b) removing supernatant liquid from the vessel; and c) adding fresh liquid to the vessel; d) using the said magnet system to draw the magnetically attractable particles to the bottom of the vessel; e) removing the magnet system; and f) re-suspending the magnetically attractable particles in the fresh liquid; and wherein the magnet system comprises a back flow plate formed of a magnetizable material and having an upper surface, and a plurality of pairs of permanent magnets each having opposed first and second ends and a peripheral sidewall joining said opposed first and second ends, the first end of each said magnet being positioned on the upper surface of the back flow plate with a N-S axis oriented perpendicular to the back flow plate, the polarity of the first and second ends of each said permanent magnet of each said pair being opposite to that of its neighbor, the peripheral sidewalls of said permanent magnets of each said pair being spaced apart to define a work station therebetween, wherein each said work station is configured and arranged to receive the bottom end of a respective said vessel therein.

Claim 5

A method of treating a solution of a polymer in a vessel having a bottom end, by the use of magnetically attractable particles which do not specifically bind the polymer, comprising the steps of: a) suspending the magnetically attractable particles in the solution so as to form a liquid suspension of the magnetically attractable particles; b) precipitating the polymer out of solution whereby it becomes non-specifically associated with the magnetically attractable particles; c) bringing the vessel into proximity with a magnet system whereby there is formed an annular or part-annular pellet comprising the magnetically attractable particles and the precipitated polymer, said pellet being positioned close to but not at the bottom of the vessel; d) removing a supernatant liquid from the vessel; e) adding fresh liquid to the vessel; f) using the magnet system to draw the magnetically attractable particles to the bottom of the vessel; g) removing the magnet system; and h) re-dissolving the polymer in the fresh liquid; and wherein the magnet system comprises a back flow plate formed of a magnetizable material and having an upper surface, and a plurality of pairs of permanent magnets each having opposed first and second ends and a peripheral sidewall joining said opposed first and second ends, the first end of each said magnet being positioned on the upper surface of the back flow plate with a N-S axis oriented perpendicular to the back flow plate, the polarity of the first and second ends of each said permanent magnet of each said pair being opposite to that of its neighbor, the peripheral sidewalls of said permanent magnets of each said pair being spaced apart to define a work station therebetween, wherein each said work station is configured and arranged to receive the bottom end of a respective said vessel therein.

Claim 6

A method of treating a solution of a polymer in a vessel having a bottom end, by the use of magnetically attractable particles which do not specifically bind the polymer, comprising the steps of: a) suspending the magnetically attractable particles in the solution so as to form a liquid suspension of the magnetically attractable particles; b) precipitating the polymer out of solution whereby it becomes non-specifically associated with the magnetically attractable particles; c) bringing the vessel into proximity with a magnet system whereby there is formed an annular or part-annular pellet comprising the magnetically attractable particles and the precipitated polymer, said pellet being positioned close to but not at the bottom of the vessel; d) removing a supernatant liquid from the vessel; e) adding fresh liquid to the vessel; f) using the magnet system to draw the magnetically attractable particles to the bottom of the vessel; g) removing the magnet system; and h) re-dissolving the polymer in the fresh liquid; and wherein the magnet system comprises a back flow plate formed of a magnetizable material and having an upper surface, and a plurality of pairs of permanent magnets each having opposed first and second ends and a peripheral sidewall joining said opposed first and second ends, the first end of each said magnet being positioned on the upper surface of the back flow plate with a N-S axis oriented perpendicular to the back flow plate, the polarity of the first and second ends of each said permanent magnet of each said pair being opposite to that of its neighbor, the peripheral sidewalls of said permanent magnets of each said pair being spaced apart to define a work station therebetween, wherein each said work station is configured and arranged to receive the bottom end of a respective said vessel therein.