Copper prices topped $12,000 a ton for the first time, extending the metal’s recent bull run as mine outages add to concerns about supply of the vital industrial metal. Benchmark prices climbed as much as 2% on the London Metal Exchange on Tuesday to $12,159.50. The metal has gained more than 35% this year and is on track for its biggest annual jump since 2009. The threat of US import tariffs on the metal has also been an important factor pushing up prices this year. Copper is piling up in American warehouses as the potential imposition of new levies prompts buyers to secure shipments and has opened up an arbitration ... (full story)