Copper prices have rebounded a bit lately, lifting some of the gloom on worldwide commodity markets.  But the increased demand from China, which needs copper for wiring and cables in its electronic products, could be about to take another downward turn.

"We've had this rally in metal prices on macro developments in China but that hasn't been supported by fundamentals," said Matthew Wonnacott, a Hong Kong-based analyst at the commodities consultancy CRU.

Copper ended up 0.5 percent at US$5,065 per ton on the London Metal Exchange.  That's still almost 50 percent down from the US$10,000 peak in 2011.  And China - which gobbles up more than 40 percent of the world's copper trade - is expected to increase its copper consumption by a wafer-thin 0.6 percent this year.  That's down from 2015's estimate of 3.8 percent growth.

Not only that, but China hasn't used some 200,000 tons of semi-fabricated wire rod that it bought up and stored last year.  For these reasons, CRU expects the current rally to end in the second quarter, and for copper prices to sink back down to an average of $4,529.