0918 GMT - The Democratic Republic of Congo's ban on copper and cobalt concentrate exports is expected to have limited impact on global copper markets, Goldman Sachs analysts say, calling it an administrative extension of the country's long-standing push to process minerals domestically rather than a new supply shock. "We estimate the remaining affected flow to be modest relative to the global market, or 0.3% of global mine supply, while the Mines Ministry retains discretion to grant waivers," they say. Copper futures trade above $14,000 a metric ton, supported by concerns over potential U.S. import tariffs and tightening inventories outside the country.