The Eldorado refinery on John Street, Port Hope, 1938. LAC a015675. After processing Canadian uranium from Port Hope, the U.S. Army Corps of Engineers purchased 1,200 tons of higher-grade uranium ore from the Belgian Union Minière in August 1942 but only the Port Hope refinery was able to process it. As Robert Bothwell writes in his company history Eldorado, “Thus, Eldorado’s principal importance in the wartime atomic energy Project was established…it was the Eldorado refinery that became crucial to the bomb Project … a critical link in the American supply chain.”