Can renewables make it in the metals industry?

Is it possible for metal makers to incorporate wind and solar without affecting quality or productivity? That’s what Perth-based Element 25 (E25) means to find out. In an industry first, E25 will test the extent to which renewable energy can be used to power electrowinning for producing Electrolytic Manganese Metal (EMM) at its Butcherbird development.

The approach is a significant departure for the metals industry. Until now, metals have been made using a flat supply of electricity from traditional sources such as grid or hydroelectric power, but under a grant from the Australian Renewable Energy Agency (ARENA), E25 will be trialing variable power. Energy consulting firm Advisian identified a hybrid energy solution as the most cost-effective option and helped procure the grant.

“It’s a new way of thinking really, and a different way of going about it. It’s going to need some engineering solutions to design a plant around a dynamic supply of electricity, which is not the traditional way of engineering these types of plants,” E25 Executive Director Justin Brown explains. “So it’s a bit cutting-edge in that regard, but the payoff is significant because the cost of deploying renewables in Australia and most parts of the world is now less than that for fossil fuels.”

POWERING BUTCHERBIRD

The trial will roll out over the next 12 to 18 months at E25’s Butcherbird site in Western Australia, one of the country’s largest onshore manganese resources. Roughly a thousand kilometers north of Perth, the location boasts more than 180 million metric tonnes of near-surface manganese oxide ore in seven deposits. The project will produce high-purity EMM and manganese sulphate for use in specialty metals and lithium-ion batteries.

While the Goldfields Gas Pipeline runs through the project, it doesn’t have infinite capacity. The energy mix will include wind and solar in addition to natural gas. At baseline, renewables are expected to make up at least 50% of the power mix. Wind will likely be the main renewable component, with solar boosting generation during the day when the wind is less intense.

“We’ve got a very, very large manganese resource at the project, and so, as we grow our production capacity, we would eventually hit limitations on gas supply,” Brown relates. “Wind and solar allow us to be independent of that, so that’s a big positive.”

TRIMMING COSTS

Metals are recovered through electrowinning, the process of passing a current through a solution. Electrowinning manganese, copper, zinc, and other metals requires a tremendous amount of power. As a result, reducing energy costs was a primary driver for E25’s decision to use renewables. Wind and solar will also give E25 a degree of independence from gas prices, insulating the company from future price volatility.

“When you’re making metals, power is the biggest part of the operating costs,” Brown explains. “Every cent that you can shave off of the kilowatt hour cost has a significant impact on the bottom line,” amounting to tens of millions of dollars.

TESTING VARIABLE POWER FOR ELECTROWINNING

When the trial comes online, it will test the viability of Intermittent Dynamic Electrowinning (IDE), in which the electrowinning process must respond to changes in power generation. Beginning with a base case of 50% renewable generation, the trial will monitor variables that impact the electrowinning of metals, including temperature, voltage, current, pH, leach solution, concentrations, impurities, and other factors. The lab work will be performed at Murdoch University’s Extractive Metallurgy Division. The goal is to optimize the process plant to push the use of renewables above baseline.

“We think we’re comfortably at 50-50 gas and renewables, and if we can push that as high as 80 or 90% renewables, that will be significant from a carbon intensity point of view,” Brown says.

“The goal is to find the range within which we can vary those parameters to allow power from a variable source without impacting quality or the productivity of the plant.”

REDUCING CARBON INTENSITY

Renewables have low penetration in the minerals processing sector—a situation that ARENA hopes this demonstration project will change. Its $490K grant to support the pilot studies will make up half of the total budget of $980K.

If the studies find the optimum conditions for electrowinning with variable power, “the use of renewables could be expanded to other types of metal processing, increasing the opportunities for Australia to export renewable energy or emission-free resources to the world,” ARENA CEO Darren Miller stated in an announcement. It could also make electrowinning possible in remote areas of Australia and other countries that don’t have easy access to grid power.

For its part, in addition to the cost savings, E25 is eyeing a competitive advantage in being the first metal maker to reduce its carbon intensity in this way.

“We see in the not-too-distant future a world where having a low carbon intensity of your product will be a marketing advantage,” Brown states. “It’s not here just yet, but low carbon intensity will be a benefit soon.”

Butcherbird’s pre-feasibility study is underway, and the trial is currently expected to be complete in the third quarter of 2020. If successful, it could pave the way for renewable energy in the metals industry and increase downstream metals processing in Australia, ultimately boosting other areas of the economy.

“Australia is currently the third largest producer of manganese ore, and if the project shows that renewables are a viable option, it could help to revolutionize the way metals are produced,” Miller states. “Rather than have the raw product exported and processed offshore using fossil fuel-based energy, the project might give birth to “a new industry in Australia where ore is processed right here using Australia’s low-cost renewable energy sources.”