Mining engineers vouch for open pit mining

MANILA, Philippines - Mining engineers believe the open pit mining method is a safe and highly productive process applicable to mining areas with high levels of deposit just like the proposed Tampakan mines in South Cotabato.

In a recent mining symposium in Davao City, Philippine Society of Mining Engineers (PSEM) president Cesar Lao and Mindanao Association of Mining Engineers (MAME) president Lucio Castillo cited the advantages of the open pit method which according to them is a safe extraction procedure and is certainly friendly to the environment contrary to the opinion of environment advocates.

“Open pit method is applicable to massive mining deposits and productivity is high,” said Lao.

The open pit mining method, according to Lao, is surface mining to extract rocks and minerals from the surface.

Mining companies choose this method of removing the top layers of the land when exploration studies show minerals are close to the surface or if a normal tunnel-type of mine is not possible.

Lao said using this method results in high efficiency and profitability because you only remove very shallow or thin portions of the surface. Then you can easily rehabilitate and let that surface return to its original physical structure.

Lao added: “If you go down (by tunneling) below, the waste to be extracted would be about 1:7 or 1:6 and that is not profitable anymore. It will create a lot of destruction in the environment.”

Lao said in open pit mining the waste-to-ore ratio is very low.

Waste-to-ore ratio (stripping ratio) refers to the ratio of the volume of waste material required to be handled in order to extract some volume of ore. For example, in open pit mining of gold, a 1:3 stripping ratio means that mining one cubic meter of ore will require mining three cubic meters of waste rock.

Responsible mining companies use the surface mining method in a sustainable and environment-friendly way, he added.

Lao said a number of old open pit mines in Australia and Indonesia have been rehabilitated. “They are now beautiful with lakes and forests because the mining companies that operated them are responsible mining companies,” he said.

Castillo, for his part, vouched for the safety of open pit mining which he said could produce voluminous metals like in Atlas Mining which produces a more than 500 metric tons of copper a day.

Sagittarius Mines Inc., the government’s financial and technical contractor for the Tampakan mines, proposes the open pit mining method. If developed, the Tampakan mines have the potential to become an economic driver for Mindanao and the entire country.