The first set Heekin Si ion exchange column by Higgins invention Oak Ridge National Laboratory in the United States, as shown in FIG.
Figure 1 Higgins moving bed ion transfer column
The entire device forms a closed loop. In the adsorption section, the resin moves upward, and the leachate flows downward in countercurrent contact with the resin. At the same time, the eluent passes through the rinsing section in a countercurrent direction.
During operation, the leachate and the leachate are intermittently entered into the column. It is switched every few minutes, at which time the resin after rinsing is pulsed into the lower part of the adsorption section. Adsorbing a period of about 5 ~ 20min, depending on the flow rate of adsorption and concentration of uranium leaching solution. When adsorbed, valves A, B, C, and D are all closed and can be rinsed at the same time. At the end of the adsorption cycle, valves A, B, C, and D are all open, and water enters the pulse section through valve 7 under pressure to force the resin to move forward along the circuit, and then several valves are closed again, and the leachate and eluent can be The liquid introduction, adsorption, and rinsing cycles are restarted. The resin moves for less than 1 min each time, so the adsorption and elution time is much greater than the resin movement time.
Wyoming Minerals two such devices built diameter 2.44m in 1977 for the recovery of uranium from copper ore leaching solution. The processing capacity of the two sets is 1727m 3 /h, the uranium concentration of the leachate is 6-7mg/L, and the flow rate can reach 163m/h. Due to the high flow rate, the pressure drop in the bed is large, causing the gel-type resin to rupture. In order to overcome this shortcoming, the length of the adsorption section was reduced from the original 2.44m to 1.525m, and the adsorption flow rate was also reduced from the original 163m/h to 110m/h. At the same time, the gel type resin is replaced with a macroporous resin having better enthalpy. The saturated resin was rinsed with 1.5 mol/L sulfuric acid, and the concentration of the uranium rich in leaching was 0.5-1.0 g U 3 O 8 /L, and the uranium was enriched to 35 g U 3 O 8 /L by extraction. Due to the severe wear of the resin and the slowing of the kinetics, it is said that the resin replaced each year is 70% of the input. Despite this, Higgins moving bed technology is still a major breakthrough in ion exchange technology.
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