China’s "brewing" copper smelter bottleneck signals deepening supply worries for a metal market that’s already seen facing shortages this year. So-called treatment charges paid in China by miners to smelters have tumbled to $56 a metric ton, the lowest in almost seven years, squeezing margins and potentially spurring more production cuts, according to Goldman Sachs Group Inc. analysts, including Alison Li. Output in the first half was curtailed after plants had their maintenance, access to credit tightened and technical issues hampered operations, the bank said.
