Copper traded near a 15-month high as supply concerns and brighter demand prospects triggered a slew of bullish calls on the market. Prices have climbed more than 15% the past two months after mine disruptions threatened refined-copper production at Chinese smelters, which account for more than half the world’s supply. At the same time, investors are betting on stronger consumption there as manufacturing picks up.  Used in power cables, wind turbines, electric vehicles and solar panels, copper is a key material for the energy transition. The metal traded little changed Tuesday at $9,419.50 a ton on the London Metal Exchange. China’s factory activity beat expectations in March, the latest sign of an economic recovery in the world’s largest copper user. Data showing increased spending also suggests domestic consumption is gathering pace. During the bull market of the 2000s, copper rose more than fivefold in three years, driven by urbanization and industrialization in China. Citigroup said there’s potential for “explosive price upside” again in the next three years. Other base metals rose Tuesday, with zinc adding as much as 2.4% as Chinese smelters become the latest casualty of overcapacity in the country’s metals markets.