| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for preventing the occurrence of calcium scale while reducing a chemicals expense and lowering an operation cost. <P>SOLUTION: The solution containing calcium ions and SO<SB POS="POST">4</SB><SP POS="POST">2-</SP>is divided, using an amphoteric ion-exchange resin 4, into a first solution having low calcium ion concentration and high SO<SB POS="POST">4</SB><SP POS="POST">2-</SP>concentration and a second solution having concentrations opposite thereof, and the first and second solutions are separately treated. Thus, the occurrence of scale by CaSO<SB POS="POST">4</SB>can be suppressed to the minimum without needing addition of sodium carbonate or the like to remove the calcium ion, and an operation cost can be reduced. Besides, the amount of lead or the like collected in the solution having high calcium ion concentration can be controlled by controlling the switch timing of the first and second solutions discharged from the amphoteric ion-exchange resin on the basis of the calcium ion concentration and/or electrical conductivity of their solutions. <P>COPYRIGHT: (C)2012,JPO&INPIT |
