First refined copper

August 1, 2012
By RACHNA LAL

Last year, the owners of the Wainivesi Mine in Tailevu, Asia Pacific Resources, commenced an upgrade to double the capacity of the plant and increase its gold recovery circuit.

Managing director, Matthew Huggan, confirmed that although faced with quite a few challenges, they started trials on the first part of the gold circuit last month with good success.

“This part of the gold circuit removes troublesome copper from the concentrate surfaces before gold is extracted.  This copper is recovered and can be sold,” he said.

“This is the first refined copper ever produced from a mine in Fiji and it is expected to add about $4 million a year to our earning.”

Mr Huggan said work was continuing and the next step was gold production from the new gold circuit.

“All the equipment is installed and hooked up for this part of the plant. We anticipate commissioning the gold part of the circuit in the coming fortnight,” he said.

“This will be done very carefully to ensure that it is all safe and working properly. Once everything is all good, we will press the button and production of gold and silver should commence.”

Mr Huggan said if all goes according to plan and the plant works for most of the year, they anticipate export earnings of $60m from the first year of full operation.

“Of this, about $1.8m will go to the landowners and about $11m will go in taxes to Government,” he said.

“The company will also be employing about 60 people in an area where the mine is the largest private investment ever made and where there is very little employment.”

Need for upgrade
What makes this mine extraordinary is that it contains a range of minerals from gold, silver and copper to zinc and lead.

One would wonder the reason behind the upgrade of the Wainivesi mine, especially since it has so many minerals that can be extracted.

In fact, it is the amount of minerals and maximizing returns from these minerals which resulted in the urgent need for an upgrade.

Mr Huggan said a lot of testing was done to ensure they could get the maximum revenue from the ore they would be mining.

“The results were good and showed we could get the zinc and copper from the mine into a condensed form (concentrate) and we could then extract most of the gold and silver from this concentrate before it was shipped to smelters,” he said.

“The importance of this was the fact the smelters would not pay us for any gold and only part of the silver.

“Without the payments for gold and silver, the revenues for the mine would be cut by more than 65 per cent and make it uneconomic.
“When we built the plant to the specifications from the testing it produced a good concentrate with the zinc and copper in it and also the gold and silver.

“But the extraction of gold and silver did not work in the way that the testing had shown in the laboratory.”

Mr Huggan said this was a common problem with ore of the type that they had at Wainivesi.

“In 2010, we had to make a decision on whether to try and extract the gold and silver or leave it in the concentrate and earn less money.  It was a big decision,” he said.

Revenue loss threat
“If we sold the concentrate we could produce, our earnings would be only 30 per cent of what we planned and for the investors it would mean no profit.

“But worse, for Government it would mean a reduction in taxes from $60m to $3m and for landowners a reduction in royalty from $12m to $3m.”

Mr Huggan said a decision was taken to invest further millions to extract the gold and silver before selling the concentrates so they could all earn more.

“A process was developed that works on the concentrates and now lets us get the gold and most of the silver out before we ship the concentrate to the smelter,” he said.

“This process puts cash back into the project and makes it viable again.  It also helps us achieve our other goals which is to deliver more money for Government to use and to give landowners a good return from their land.

“So then we had to build the plant to extract the gold and silver.

“At the same time we thought it was the best timing to bring forward our planned mill expansion and double our throughput.

“Otherwise we would just be selling our concentrates still with the gold and silver in it and losing all that income until the new gold circuit was completed.”