RENEWABLES IN THE METALS INDUSTRY
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
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