And what is the problem with that? If China wants to subsidize African development or consumption, what is the problem with that? If China loans more to African nations than they can repay, it is a loss for China, not for the African nations.
The real problem, it seems, is that China has an excess of USD that it does not know what to do with. It is afraid to let Yuan appreciate and let the Chinese people enjoy increased consumption, as while the economy is shifting from export to internal consumption there would be a period of instability - the status quo bias.
It is also afraid of buying assets in the US and Europe as it cannot guarantee that these assets will not be seized if need be for political reasons. Furthermore, it does not want to do anything that would reduce the value of the remaining dollars it holds. Trying to establish a resource base in Africa where they can build relationships, influence, enforce their property rights and protect trade routes, seems like a reasonable choice.