PURPOSE: To make the specific gravity of particles high by a method wherein the particles are treated with a metal-salt solution.
CONSTITUTION: As a metal salt used to make the specific gravity of the title particles high, a tin dichloride aqueous solution at 20 to 60W/W% is normally used. The usage amount of the metal salt is usually set at the weight of five times or higher of an rodinary carrier. Although the treatment tide differs depending on the kind and the amount of the carrier, it is usually 30 minutes to two hours. A treatment temperature is at 15 to 25°C of ordinary room temperature. After the metal salt has been treated, the carrier is separated and treated with a buffer solution. As the buffer solution, a phosphoric acid buffer solution at about pH6 to 8 is usually used. As the usual buffer solution, e.g. a citric acid buffer solution can be used. A treatment temperature is 20 to 90°C, and preferably it is 50 to 80°C. After the carrier has been treated with the buffer solution, it is filtered by a filter, it As separated centrifugally, it is decanted or the like so as to perform a separation operation, and the carrier whose specific gravity has been made high can be obtained. Thereby, the sedimentation velocity of the title particles can be made fast and the judgment time of the title method can be shortened.
IWATSUKI MAKOTO
IMAGAWA YOSHITAKA
HIRAI TAKENORI
AJINOMOTO KK
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