The closest locomotive I can find to the one pictured is a South African Class 16E, but your photo depicts a locomotive with one more set of drivers. Other than the extra set of drivers it is a visual match. Don't know what other differences there may be.
I cannot find a locomotive with that wheel arrangement and other physical attributes, but I suspect it is a South African design.
It could be a Class 15E but the model in your photo does not have the wind boards along the front side of the boiler.
There isn't a dedicated sand-dome, from appearances, and it sports a Wooten firebox, also apparently. It has a front end throttle. No feedwater heater. I don't recognize the herald, or whatever that ornament is, on the smokebox cover, below the headlamp. The crosshead looks to be one for Walschaerts.