This Small Business Innovation Research (SBIR) Phase II project aims to develop a new method for primary production of magnesium from its oxide ore using Solid Oxide Membrane Electrolysis. Unlike other primary metal processes, this approach emits no direct CO2, has no chlorine, and is fully continuous and automated. Published third party cost modeling has indicated that its costs are lower than all existing and proposed new processes. Building on an earlier feasibility demonstration using experiments and mathematical and cost modeling to show that the approach can produce oxygen as well as magnesium at high current efficiency and at costs close to the published cost model, this Phase II project will develop new anode tubes to further reduce energy costs, and build and test the first self-heating electrolysis cell. If successful, the self-heating cell will not require energy beyond that needed for electrolysis and will be the smallest possible pre-production modular unit capable of producing magnesium.
The broader/commercial impact of this project begins with substantial reduction of the cost and environmental impact of magnesium metal production. Magnesium is the lowest-density engineering metal and third most abundant metal in the earth's crust, and its stiffness-to-weight, castability, and recyclability make it the best material for motor vehicle weight reduction. Automobile makers are seeking to increase the magnesium alloy content of vehicles from 10-15 lbs/vehicle to 350 lbs/vehicle by 2020, replacing 650 lbs/vehicle of steel and aluminum parts. This will increase fleet fuel economy by 1.5-2 miles per gallon, reducing annual petroleum import expenditures by about $20 billion. If successful, this project will address the biggest barrier to widespread magnesium use in vehicles, which is its price stability and availability. This could lead to a new magnesium economy taking full advantage of its light weight and ease of manufacturing in products from cellphones to laptops to trucks. With broader usage, the versatile process resulting from this development project can likely reduce the cost and environmental impact of reducing metal oxides, leading to a new industrial ecology of primary metals production.
INFINIUM is developing a new process for primary production of magnesium from its oxide. Our process, known as Pure Oxygen Anodes™, uses molten salt electrolysis with a zirconia solid electrolyte sheath between the molten salt and liquid metal anodes. After demonstration of likely feasibility using modeling in Phase I, but before this Phase II project, the main remaining areas of cost challenge or uncertainty were: zirconia tube lifetime, energy usage, and performance at larger scale. This project achieved several significant results toward commercialization. First, it demonstrated early on that energy usage is not a major issue, thus an original objective of developing a thin zirconia tube became a low priority. It then developed multiple techniques and process modifications to extend projected zirconia tube lifetime to as long as 4000-5000 hours, likely removing tube lifetime as a barrier to commercialization. Second, it developed a low-cost oxygen-stable current collector with long-term stable operation in an anode generating pure oxygen. This will enable production of a valuable oxygen by-product while also producing metal. Third, it demonstrated operation at high anode current density, making anodes very productive. This reduces the effective anode and zirconia tube cost per unit of metal output. Fourth, it demonstrated the largest magnesium production furnace to date, with eleven zirconia tubes in a steel shell controlled-atmosphere furnace having an internal heating element. Fifth, it developed a novel argon recycling method which recirculates argon exiting the magnesium condenser, pumping it back into the crucible. No impurity gases were found to accumulate during normal cell operation, but hydrogen and sulfur are possible contaminant gases, and the project led to invention of a very low cost filtration medium for removing both of those gases from argon. With all of these scientific and engineering breakthroughs behind us, the project is ready for rapid scale-up toward industrial implementation. Because this technology is very energy-efficient and uses low-cost magnesium oxide raw material, it is very likely to be the lowest-cost method for producing magnesium metal, with much lower cost than either of the two dominant methods today. Furthermore, this technology is very modular, such that it can scale down cost-effectively to "magnesium mini-mills" for on-site production at a MgO plant, or scales up easily by mass production of welded steel cells for a large production facility for example at locations with low electricity cost. It produces a high-purity oxygen by-product, and unlike other magnesium processes emits no CO? or chlorine -- its only emission is a trace amount of SO? from the raw material. This project supported publication of two refereed journal articles, nine conference proceedings and other papers, one Ph.D. thesis, and two patent applications. Fifteen participants, including five undergraduates, developed new skills and understanding of thermodynamics, kinetics, electrochemistry, and high-temperature experimentation. More broadly, technology developed in this project is having an enormous impact on the field of primary production of metals. This technology is emerging as the lowest-cost most energy-efficient highest-quality lowest-emissions method for producing rare earth metals such as dysprosium and neodymium used in the strongest permanent magnets. In September 2013, INFINIUM won an ARPA-E grant to test its feasibility for producing aluminum, bringing its benefits of energy efficiency and near-zero emissions to a $100B industry. And co-investigator Uday Pal is working on using this anode technology for single-step production of solar-grade silicon directly from naturally occuring quartzite. Magnesium is a wonderful engineering metal, with the best stiffness-to-weight and strength-to-weight ratios of all metals. Today it is widely used in mobile phone and laptop computer cases, but its cost and emissions have limited its use have been prohibitive for broader use in very light-weight automotive bodies. This project will likely reduce pollution emissions associated with magnesium production below that of the steel and aluminum it replaces, reducing emissions throughout the production-use-recycling vehicle life cycle. Clean low-cost rare earth metal production will have a similar impact on fast-growing industries such as wind turbines and hybrid and electric vehicle drive motor/generators. And low-cost solar grade silicon will further reduce the cost of solar wafers, cells and modules, bringing even more markets below grid price parity. Geopolitically, the ability to economically produce magnesium and rare earth metals outside of China will likely have a very large imact. US auto makers are not willing to gamble on commodities such as magnesium whose price has fluctuated wildly over the past ten years at the whim of the Chinese government. INFINIUM's Pure Oxygen Anodes™ technology could thus free these markets from Chinese control. In short, thanks in large part to its first funding from the NSF SBIR Phase I and this subsequent Phase II project, INFINIUM is ushering in a new Clean Metal Age, in which clean energy and energy efficiency technologies are not compromised by "dirty" and politically problematic production of the metals they use.