SANTIAGO, Aug 13 (Reuters) - The head of BHP-controlled

Escondida, the world's largest copper mine, on Thursday urged

Chilean authorities to provide legal, regulatory and tax

certainty to help copper mining projects move forward,

underscoring global demand for the red metal.

Alejandro Tapia, head of Escondida, which is located in

northern Chile, spoke at an industry event.

* BHP expects global copper demand to nearly double

by 2050 to around 50 million metric tons a year, requiring major

investment to expand and maintain supply, he said.

* "To attract this investment, we need certainty: legal,

regulatory, tax certainty, and permitting processes that are

predictable," Tapia said.

* Tapia said Chile's mining industry faces steep challenges,

including aging deposits, deeper mines, rising costs and more

complex ore, all of which are eroding productivity at existing

operations.

* He welcomed recent government moves to speed up project

approvals and improve certainty for investors, including new

legislation on sectoral permits.

* BHP was not calling for weaker environmental rules, Tapia

said.

* "We are not seeking a more lax environmental system,"

Tapia said. "What we want is predictability so we can keep

moving forward."

* BHP has an investment pipeline of about $10 billion at

Escondida over the next seven to eight years, including a new

concentrator expected to cost more than $5 billion.