Reducing Greenhouse Gas Emission from the Neodymium Oxide Electrolysis. Part II: Basics of a Process Control Avoiding PFC Emission
Open Access
- 1 January 2017
- journal article
- research article
- Published by Scientific Research Publishing, Inc. in International Journal of Nonferrous Metallurgy
- Vol. 06 (03), 27-46
- https://doi.org/10.4236/ijnm.2017.63003
Abstract
The neodymium electrolysis produces unnecessary high emission of CF4 and C2F6. These perfluorocarbons (PFCs) are potent greenhouse gases and are not filtered or destroyed in the off-gas. A process control in analogy to the aluminum electrolysis can reduce the PFC emission to a great extend and keep the process in a green process window. Therefore, a theoretical analysis is done of the cell voltage of the industrial neodymium electrolysis in dependence on the neodymium oxide concentration in the electrolyte. The analysis shows the different contributions to the cell voltage focusing on the impact of the anodic overvoltage on the cell voltage, by which the electrolysis process can be controlled. The model of the cell voltage is evaluated by laboratory neodymium electrolysis with a similar setup as the industrial cell. The relation of the oxide concentration, the anodic current density and the cell voltage with the cell resistance are measured. The continuous off-gas measurements show the gas concentration and PFC emissions. The effect of Nd2O3 feeding on the galvanostatic electrolysis is analyzed as well. Based on the results a process control strategy is proposed similar to the aluminum electrolysis strategy. The green process window is in a narrow oxide concentration range, making a continuous and precise oxide feeding essential.Keywords
This publication has 4 references indexed in Scilit:
- Reducing Greenhouse Gas Emission from the Neodymium Oxide Electrolysis. Part I: Analysis of the Anodic Gas FormationJournal of Sustainable Metallurgy, 2016
- The voltage of alumina reduction cells prior to the anode effectJournal of Applied Electrochemistry, 2002
- On the cathodic overvoltage on aluminium in cryolite-alumina melts—IElectrochimica Acta, 1978
- Determination of the electrical properties of graphite at high temperaturesPowder Metallurgy and Metal Ceramics, 1962