Miner BHP Billiton has made record half-year profits thanks to strong demand and high prices.

Net profit jumped 72% to $10.52bn in the six months to the end of December, BHP said.

It also unveiled plans to spend $80bn on new projects worldwide, and buy back $10bn of shares from investors.

BHP said it saw demand growth slowing in 2011, but added that economic conditions should help earnings.

“While we expect a slowdown in the growth rate of global commodity demand in calendar year 2011, the economic environment still underpins a robust near-term outlook for our products,” chief executive Marius Kloppers said.

The company said it plans to spend the $80bn over the next five years as it looks to develop new projects. BHP said that it would use the money to develop projects in Australia, Chile and Canada.

It said iron ore shipments from its Western Australian projects were a record annualised 148Mt/y rate from the December 2010 quarter