AZU ISHIEKWENE FOR BIRD STORY AGENCY WHEN Africa’s richest man, Aliko Dangote, was dealt a bad hand in a failed transaction, he didn’t give up. Instead – slowly, steadily – he exacted his revenge. His reward? Not a pound of flesh, but millions of barrels of liquid black gold. In 2007 Bluestar, a Dangote-led consortium paid US$721 million for the moribund Port Harcourt and Kaduna Refineries. Months later President Umaru Musa Yar’Adua’s government decided to reverse the sale. The decision was driven by a labour strike and labour groups’ insistence that the refineries (which were only producing at about 20% of their…