*2.3. Experimental Procedures*

#### 2.3.1. Chemical Precipitation

Chemical precipitation procedure was used to remove potassium in this experiment. In the process, the potassium which was in simulated brine would be selectively precipitated as potassium perchlorate by adding perchloric acid. Removal of potassium could reduce the co-extracted effect in the solvent extraction process. The parameter of chemical precipitation such as effect of pH value was investigated. Precipitation rate was calculated according to Equation (1) and the flow diagram is shown in Figure 1.

$$\mathbf{P}(\%) = \frac{[\mathbf{M}]\_0 - [\mathbf{M}]}{[\mathbf{M}]\_0} \times 100\tag{1}$$

**Figure 1.** Flow diagram of chemical precipitation.

P is Precipitation rate, [M]<sup>0</sup> is metal concentration of leach liquor, [M] is metal concentration of leach liquor after precipitation.
