Public offering of Aliko Dangote’s Nigerian oil refinery business could swell his net wealth by two-thirdsThe fortune of Africa’s richest person could swell by two thirds to nearly $60bn (£44bn) after his refinery in Nigeria listed publicly in the continent’s biggest-ever initial public offering.If Monday’s flotation of Dangote Petroleum Refinery and Petrochemicals on the Nigerian exchange goes to plan, then Aliko Dangote will add a further $23bn (£17bn) to his $35bn net worth. Continu