By Nelson Banya and Sonali Paul HARARE/MELBOURNE (Reuters) -European and Asian coal importers are expected to join the scramble for alternative sources of the fuel as a European Union ban on Russian coal imports looms, analysts and company officials said. But with top exporters Australia and Indonesia having already hit production limits and major producer South Africa constrained by logistical problems, some importers may struggle to maintain supply levels. The expected rush is likely to keep global coal prices elevated. The EU ban is to take effect from mid-August, a month later than initial…