Only really significant mining interests in Guinea, so not really a sufficient explanation of the vote.
Mali, CAR, and Burkina Faso are about military/security links. Mali and CAR brought in Wagner to fight for their governments, while Burkina will probably look to do the same after their military coup.
No Russian mines in Ethiopia, Sudan, or Uganda. Ethiopia is angry about Western criticism because of their civil war and Sudan also under a military coup and looking to expand relations with Russia following it. Uganda says they abstained because they're new chair of nonaligned movement.
The Southern African countries have sympathy for Russia because of USSR support of their liberation movements.