Mining firms in Chile, the world’s No.1 copper producer, are cheering a rally in the price of the red metal that hit a 10-year high this week, but warned that costs could rise as labor unions and vendors also try to cash in on the trend.Benchmark copper on the London Metal Exchange climbed this week above $9,000 a tonne for the first time since 2011. Analysts said they were bullish that surging demand from the power and construction industries will overwhelm supply. The price spike has prompted top financiers from JP Morgan to Goldman Sachs to predict a commodities “supercycle” similar to that of the early 2000s when ... (full story)