METALS-Copper ticks higher as China returns, trade talks loom

London copper prices edged higher for a second day on Tuesday as the return of traders from a week-long holiday in top consumer China led to some renewed buying, while uncertainty over a U.S.-China trade deal pushed other metals lower. Chinese Vice Premier Liu He, U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin, will begin trade talks in Washington on T