Have industrial metals bottomed out? After what has been a fairly uneventful year for non-precious metals, the recent uptick could be a good sign for the commodities. More importantly, it could signal more robust economic growth is on the way. There are a couple factors which support the bullish case for copper and other industrial metals. First off, Goldman Sachs (GS) just upgraded Alcoa (AA), the world's largest aluminum producer. Goldman states the company's growth in high margin aluminum products and lower cost structure as reasons for the upgrade. However, the company certainly wouldn't warrant a 'Buy' rating without higher expected demand for aluminum. What's more, lower oil prices is making it easier for the world's economies to grow - and providing another catalyst for growing industrial metal demand. It will be interesting to see where prices go from here.