Not ex Africa, but I calculated mileage for the following LONE4 avoiding NA.

ZRH (BA) xLHR (QF) xSIN (JL) NRT (JL) CGK (CX) HKG (CX) BOM (QF) SYD (QF) PER (QF) AYQ (QF) MEL (QF) AKL (LA) SCL (LA) CCS (LA) xSCL (LA) LIM (LP) EZE (IB) xMAD (IB) DME (IB) MAD (IB) ZRH

It uses all 20 segments and comes up to 57,000 flown miles (IIRC), so depending on class of travel/status/etc. you might earn more than that.

You can even maximize further (especially SWP and SA), since this itinerary is a combination of interest in some locations & mileage maximization. I optimized for L class earning into the QF FFP (therefore minimizing segments on BA, CX, JL and using QF, IB, LA where possible)