Question raised over MCC claims on Ramu mine spill

Martyn Namorong

Questions are being raised over claims by the Chinese Miners [MCC] and their Australian Partner Highlands Pacific as to the accuracy of their claim that

“the spill did not involve  sulfuric acid as some locals have reported… sodium hydroxide is a much less caustic than the acid.”

Firstly, the statement by MCC Ramu Nico confuses the chemistry of both substances. SULFURIC ACID is a STRONG ACID and SODIUM HYDROXIDE (NaOH) is a STRONG BASE. They’re both equally “CAUSTIC”. It is therefore misleading to say that sodium hydroxide is less caustic.

The folks at MCC and Highlands Pacific can do a little chemistry lab experiment on whoever wrote that press statement to prove to us that NaOH “less caustic”.

A document that is publicly available on the Highlands Pacific website, states at page 7:

“A sulphuric acid plant producing 3,350 tonnes per day of 98.5% pure sulphuric acid will be installed to supply the acid requirements for the high pressure acid leach, lime boil and solvent extraction stages within the refinery. Feed stock for the plant, comprising some 360,000 tonnes of sulphur per annum will be supplied to the site by bulk shipping over the project dedicated deep water port. The acid plant will produce a large amount of steam, which will be efficiently utilised for various process heating requirements.”

According to an April 17th 2012 update by Highlands Pacific, load commissioning of the Ramu Mine project continues today. The update states:

“The mine commenced treating ore through one of the three high pressure autoclaves on 4 March 2012 and has now been operating continuously for 6 weeks with no major processing issues. In that time the process plant has treated 300,000 tonnes of slurried ore producing 486 tonnes of mixed nickel cobalt hydroxide intermediate product.”

What these two documents reveal is that a LARGE AMOUNT OF SULPHURIC ACID and limestone has been used by Ramu Nicco to treated 300, 000 tonnes of ore producing 486 tonnes of mixed nickel cobalt hydroxide.

Using Highlands Pacific’s formula of 0.2 tonnes of Sulphuric Acid per per tonne of dry ore, [0.2 tonnes Sulphuric acid X 300 000 tonnes ore] [found on page 6] we estimate that 60 0000 tonnes of Sulphuric Acid has been used during the Commissioning Stage since the 4th of March 2012.

Now, 60 000 tonnes of Sulphuric Acid is a lot of ACID for the Chinese to play with. Do you trust them when they say:

“the spill did not involve sulfuric acid as some locals have reported… sodium hydroxide is a much less caustic than the acid.”