The South African Nuclear Energy Corporation (Necsa) is expanding its technology portfolio of speciality gases. (Necsa subsidiary Pelchem has long been renowned for its production of fluorochemicals, including gases and acids.) Not only is the group adding production capabilities for a new product but, perhaps even more importantly, it has developed a new way to produce it, which also increases the purity of the product, while reducing costs.
“The new process was developed to produce phosphorous pentafluoride (PF5) gas. “This is produced [overseas] by using more expensive and more complicated methods,” reports Necsa research and development (R&D) senior scientist Mpho Lekgoathi. “It is the intention of the project team to change this undesirable status in future. “The project started in 2012, under the Fluorochemical Expansion Initiative of the Department of Science and Technology.” (It actually began as part of his PhD research, which is now complete.)
“We have a laboratory process for the production of the gas that is fully functional,” he explains. “We have completed the process flow sheet that will inform the final design of the plant that will use the new technology on a commercial scale.”
“PF5 is a precursor for lithium hexafluorophosphate (LiPF6) as well as being a catalyst for polymerisation reactions and a strong fluorinating agent employed in organic synthesis,” explains Necsa technology transfer intellectual property (IP) analyst Tandokazi Nquma. LiPF6 is an electrolyte component for lithium-ion (Li-ion) batteries. “We have filed for formal IP protection. The project team is embarking on a process to raise funds for further development of the technology.”
Calcium fluoride obtained from fluorspar is used as a basis of Necsa’s new process. “South Africa has the largest fluorspar reserves in the world, but is only the number three producer and 95% of our production is exported for beneficiation elsewhere, with only 5% beneficiated in South Africa,” notes Lekgoathi. “This process could increase the proportion of the mineral beneficiated in South Africa.”
The main target market is the Li-ion battery industry. Li-ion batteries need the high purity electrolyte that the new Necsa process has the potential to provide at a relatively low cost. Such high-quality electrolyte prevents these batteries from overheating when being charged and also extends the life of a number of battery components.
The Li-ion battery industry reached $11-billion in sales in 2012, a figure that is forecast to grow to $35-billion by 2020. Although best known to the public for their use in cellphones and laptops, Li-ion batteries are increasingly being used in electric cars, commercial aircraft and for bulk energy storage systems (particularly as elements in renewable-energy systems).
The Applied Chemistry Department of Necsa R&D focuses on developing products based on the technology platform of fluorine and hydrogen fluoride. Using this platform, Necsa has in the past developed commercial products like xenon difluoride, nitrogen trifluoride, organic fluorochemicals and several others that are produced and sold in international markets through its subsidiary, Pelchem.