From my understanding, haven't looked into it for a while, there is actually no CGT in the DRC and any gains are simply classified as income. They have however had issues in the past with companies incorporated elsewhere circumventing said tax but it is now classified that earning made domestically within the DRC are considered taxable by the DRC at their corp tax rate (30% on mining).
However, there may be some nice creative accounting at play that allows them to write down the gain (classified as income, not capital like here) down to zero through other losses. We don't have the whole detail but simply saying transferring from one entity to another with 50% owned by another owner isn't simply tax free.
Im sure they have thought this stuff through though and its prob a non-event as they would have known the 'tax value' at the time of the acquisition.
