Characterization of the thermal flux transferred by the plasma arc to the surface of the liquid bath in the Plasma Arc Melting Cold Hearth Refining process (PAMCHR)

Abstract

Europe is a major provider of titanium scrap but until now there has been no european facility dedicated to the production of aeronautical quality titanium alloys by recycling. UKAD, a joint-venture between Aubert & Duval and UKTMP, ADEME and Crédit Agricole Center France, created the company EcoTitanium, where the recycling of machining scraps is achieved using the Plasma Arc Melting Cold Hearth Refining (PAMCHR) process with the aim of producing such alloy ingots. The determination of the heat flux transferred from the plasma column to the surface of the liquid bath is an important issue needed for the development of a future 3D process modeling based on Ansys-Fluent CFD software. With this preliminary aim of predicting the heat flux, a study coupling pilot furnace testing and numerical modeling has been performed. Melting tests were carried out in a pilot PAMCHR furnace in MetaFensch, with a stationary torch. In parallel, the different contributions of the heat flux transferred to the surface of the liquid bath were identified and implemented in a simple 2D axisymmetric heat transfer model. Numerical results are compared to the experimental measurements, in order to define the heat flux transferred from the plasma torch.