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Where will the water come from for Julimar nickel mines?

Doug Blandford*

THREE more companies, Australian Silica Quartz Group Ltd, DevEx Resources Limited which are now associated through an earn-in agreement, and Cassini Resources Limited have thrown their hats into the ring and joined the exploration bandwagon in what is now known as the Julimar Nickel Province.

Cassini Resources is also drilling for nickel copper cobalt and platinum group elements about 20km south of New Norcia, approximately 45km north of the Chalice discovery at Julimar.

Once a mineral province or complex is recognised, and multiple exploration/ mining companies are involved in its development, the potential for environmental impacts increases exponentially.

The reasons for this are many and varied, and there is also the possibility that there could be three individual nickel-sulphide mining ventures located along the Western Darling Plateau all within 100km from the Perth CBD.

Economic viability may suggest that infrastructure for transport, processing, and refining, could be shared.

It would seem logical to set up a central and major processing facility but differences in the mineralogy of each ore body will almost certainly influence this as differences in ore type and quality may require different processing systems.

But it would also seem logical for each mine site to have, at least, its own crushing and concentrator system which would then require each mine site to have the appropriate supporting infrastructure.

The characteristics of the various ore bodies, and the volumes of concentrate needing transport, will both influence the value of having a central smelter.

Such a plant will require larger and individual processing area stockpiles for ore. This then further complicates the problems of on-site roasting, such as stack emission air quality and plume dispersion dynamics.

On-site smelting also introduces the need to transport large volumes of refined ore product to the coast for shipping by either rail or road.

The reality is that there is the potential for up to three nickel-sulphide mines to be developed in the Julimar Nickel Province with each site having its own concentration and refining plants and transportation systems.

All this would occur within 100km of the Perth CBD, so let’s talk about water supply.

After air quality issues, and that includes stack emissions and fugitive dust from mining and processing operations, water supply will become a major issue for any proposed nickel-sulphide mining venture in the Perth Hills.

CSIRO data indicate that for the year 2020 the mining industry in WA will use 940 million tonnes of water. That’s a lot of water.

The need for water is a double-edged sword.

Finding it and getting access to it is one thing. Extracting it and delivering it to the mine area, without impacting the human and biological environment is another.

Water availability is also diminishing. The discharge of the Avon River at Toodyay in 2019 was approximately 44.04 billion litres which is well below the long-term median of 64.18 billion litres.

A well-established nickel mining and processing operation south-east of Wiluna uses approximately 11 million tonnes of water a year, water that is sourced mainly from three remote bore fields and pit dewatering. Down south, the Ravensthorpe laterite nickel operation pumps water from the ocean for its use.

The area of the local nickel-sulphide discoveries is in the western Yilgarn Craton which is not a groundwater area. Further, the aquifers in the Swan Coastal Plain should not be available to the mining industry because of falling water tables.

Under the Rights in Water and Irrigation Act, 1914, the general area of exploration and potential mining development is within a Proclaimed Surface Water Area covering the Avon River System, and the Avon River Catchment Area.

So, where will the water come from to support a single nickel-sulphide mine located some 18km inland from the Darling Scarp? And what if there are three new nickel mining ventures?

It is reasonable to suggest that the total water requirement could be anywhere between 25 to 35 million tonnes of water per year.

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

 

 

 

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