Ores mining methods (extraction of these ores + installation of the flotation device + roasting unit) Could it be the richest city inside the state of congo Lubumbashi is 1 Among the many richest city in the nation and it’s also the hub of many mining companies in DRC congo. http://brooksozcee.ampblogs.com/Top-latest-Five-lubumbashi-business-directory-Urban-news-40370581