19/12/2007 - 22:00

Heap leaching trials crank up

19/12/2007 - 22:00


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A fresh wave of nickel miners is hopeful a new processing technology will realise significant cost benefits, as trials into the feasibility of heap leaching on laterite nickel deposits move into full swing in Western Australian.

A fresh wave of nickel miners is hopeful a new processing technology will realise significant cost benefits, as trials into the feasibility of heap leaching on laterite nickel deposits move into full swing in Western Australian.

Heap leach, a cost-effective and viable method for nickel extraction common in gold and copper production, is being touted as the next growth area for nickel production.

Globally, there are a number of demonstration plants testing the feasibility of large-scale heap leach processing operations. In WA, the most advanced trial is occurring at Minara Resources Ltd’s Murrin Murrin operation, where it has been running a pilot demonstration plant for almost a year.

Other nickel miners, including Heron Resources Ltd, GME Resources Ltd and Barra Resources, are all in the early stages of developing heap leach processing facilities.

Junior player Nickelore Ltd, formerly Halcyon Group Ltd, has flagged its intentions to develop a commercial heap leach plant in 2010-2011 at its Canegrass laterite nickel and cobalt operation, 70 kilometres north west of Kalgoorlie.

Managing director Iggy Tan, who joined the company in July, said heap leach had a number of benefits over other widely-used extraction processes, such as high pressure acid leaching (HPAL), including lower capital and operational costs, and lower technical risk.

On the downside, the process has a lower recovery rate than HPAL and takes longer – between 100 and 300 days – for the acid to percolate through the ore pile.

But Mr Tan believes the low-cost alternative will allow smaller players to enter the market, as the rising demand for nickel globally forces miners to increasingly look to lower-grade laterite deposits.

“The age of laterite also has to come into play,” Mr Tan told WA Business News.

“There is a need for laterite deposits to be developed to keep up with demand.”

With mineral rights over a total of 140,000 tonnes of nickel, Nickelore is looking to fast track its development program.

With the completion of the scoping study expected in the first quarter of 2008, the company will then launch its pre-feasibility study with a view to commencing construction of the plant in 12 months’ time.

Mr Tan estimates costs of about $600 million for the project.

Meanwhile, Minara’s demonstration plant started operation in January 2007 on the back of a four-year $20 million research and development program.

Minara has invested between $75 million $80 million on the project, including a commitment of $25 million to further expand the heap leach pad area.

The plant is designed to produce a further 2,000 tonnes of nickel when fully operational, with the ability to be expanded to between 8,000t and 10,000t if the first stage is successful.

The company is expected to decide whether it will pursue a major expansion of the heap leach project in late 2007 or early 2008, with the first stage of the expansion taking the current demonstration plant to a commercial scale project.

Other major heap leach trials being undertaken in WA include GME Resources’ NiWest Nickel Laterite Heap Leach Project and Heron Resources’ Jump-up Dam Heap Leach Nickel Project.

Last month, GME signed an agreement with Norilsk to conduct the trial heap leach program at its Cawse Nickel plant site.

Construction of the site is expected to start in March 2008.

Heron Resources is in the process of commencing trial mining and construction of its $10 million demonstration leaching project.

Heron managing director Mathew Longworth said he estimated the cost per pound of nickel production using heap leach processing was between $13-$14, compared with about $28-$30 for HPAL.

But while the process did offer cost benefits, he said miners needed to be sure it was refined and the technical challenges ironed out in the trial phase.

“There has been some successful demonstration of the technology both in Turkey with European Nickel and Minara, but every deposit is different,” Mr Longworth said.

Another Perth-based company involved in this space is Pacific Ore Ltd, formerly Trajan Minerals Ltd, which has developed its own BioHeap bacterial heap leaching technology.

Following on from successful trials in WA, the company has established a 4,500t/year year pilot plant in northern China for extracting copper.



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