GB1034223A - - Google Patents

Abstract

1,034,223. Removal of radioactive contaminants from milk. CHEMICAL SEPARATIONS CORPORATION. April 1, 1964 [April 1, 1963], No. 13423/64. Heading A2E. A continuous process for the removal of radioactive contaminants from milk comprises (i) acidifying the milk to reduce its pH to between 5 and 6; (ii) flowing a first portion of the milk into the decontaminating section of a cation-exchange column loop having a shiftable cation exchange resin bed therein, thereby exchanging strontium 90 cations for at least one cation of the class calcium, magnesium, sodium, and potassium; (iii) simultaneously treating a second portion of the resin in a regenerating section of the loop by contacting with a balanced aqueous solution of calcium, magnesium, sodium, and potassium chlorides; (iv) substantially simultaneously interrupting the flow of milk and regenerating solution; (v) shifting the resin bed from one section of the loop to another contiguous section, thereby replacing at least a portion of the resin in the decontaminating section with a portion of resin which has been regenerated, and displacing a portion of the spent resin from the decontaminating section and transferring it to the regenerating section; (vi) re-establishing the milk content of the decontaminating section, whilst maintaining this section free from any other liquid; (vii) simultaneously flowing a second porteion of acidified milk and regenerating salt solution through the decontaminating and regenerating zones; (viii) repeating (iv to (vii) as often as required, and (ix) treating the milk removed from the decontaminating section to restore the original pH of the milk. Step (ix) may be effected in an anion-exchange column, operated in substantially the same fashion as the cation-exchange column described, regeneration being effected by an aqueous alkali solution. This process will at the same time remove iodine-131 from the milk. The acidification of step (i) may be effected by the addition of hydrochloric acid, or alternatively the milk may be passed through an electrolytic cell, wherein basic metallic cations are replaced by hydrogen ions, and step (ix) is effected by flowing the milk through another electrolytic cell, wherein hydrogen ions are discharged and basic metallic cations are reintroduced. The regenerating salt solution may itself be regenerated for recycling, for example by adding an aqueous solution of strontium chloride and calcium sulphate to precipitate the strontium 90 as the sulphate, maintaining the mixture at 80-95‹C. for about 1 hour, filtering, and restoring the thus-recovered solution to its original composition. Alternatively, the solution may be contacted with a cation-exchange resin having a high affinity for strontium, eluting the strontium from the resin by means of sodium ions, precipitating the strontium by means of sodium carbonate and ferric chloride, filtering to recover a reusable sodium ion solution, and subsequently conditioning the sodium-form cation exchange resin with a solution of calcium, magnesium, sodium, and potassium chlorides for reuse.