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Waste dumps and tailings in Julimar?

By Doug Blandford*

I READ with interest the article in the May edition of The Toodyay Herald regarding the results from exploration drilling in the Julimar area west of Toodyay.

There is no doubt that the initial results confirming the presence of nickel, copper and the platinum group elements (PGEs) including palladium, is significant in terms of both supply and demand at a global scale.

There are many issues in having a highly attractive ore body in close proximity to Perth and port facilities.

Such proximity suggests massive cost savings for the miner.

Any mining operation associated with the extraction, processing, and refining of a nickel sulphide ore body, and particularly one containing the platinum group elements will have a suite of potential environmental impacts.

Such a mine will require waste dumps and tailing storage facilities and the infrastructure associated with a mine of this type.

This means a crushing plant and a concentrator/drying plant.

The concentrated ore then needs to be processed to extract the minerals and the type of ore body suggests that this would involve two stages, a pyrometallurgy stage and a hydrometallurgy stage.

These are smelting and flotation plants.

They are big and they are complex.

The presence of such infrastructure in the hills environment of the ore body, would change the local area to an industrial complex.

The project is very much in its infancy at this stage, but the ore still has to be treated to produce a saleable product.

If the processing does not take place on site, then it has to be transported to a facility that can accommodate the required infrastructure.

A lot really hinges on the processing and refining systems technology available, and appropriate for specific mineral extraction.

The presence of palladium and associated minerals adds a further complex system to the extraction process.

At the time of writing this letter, the spot price of palladium was about $92,000 a kilogram.

There will be some interesting trade-offs between on-site processing and refining and sending a concentrate elsewhere for refining.

Any form of on-site pyrometallurgy must be examined very closely in terms of stack emissions and plume dispersion over the proximal Swan Coastal Plain and the eastern and northern suburbs of Perth.

What we would call the ‘zone of influence’.

Experience from plume dispersion modelling from the Gidji Roaster, which was decommissioned in mid-2015, showed that even from this site, which was 15km north of Kalgoorlie on the Goldfields Highway, a contaminant plume (the roaster stack was 180m tall) moved down to the coast and out to sea, only to be returned to the coastal plain with the south-westerlies later in the day.

The next stage of this project will involve further exploration drilling and ‘infill’ drilling to tighten up on ore body dynamics.

If exploration moves into the Julimar State Forest, the State regulators must require strict environmental management conditions as part of the approval to drill within the boundaries of the forest.

As a minimum, a botanist and zoologist should accompany all exploration activities to ensure that the habitat of the now well-established Chuditch, or Western Quoll (Dasyurusgeoffroii) is not disturbed and that exploration activities are not carried out within 50m of rare flora.

This will indicate how seriously the regulators, at both the State and Federal levels, will be in addressing environmental protection and management of the potential impacts resulting from project implementation.

And air pollution of the Perth environment on the coastal plain and the western Darling Plateau is just one of them.

* Toodyay resident Doug Blandford is a retired Environmental Earth Scientist.

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