Launder System for Aluminium Casting

Abstract

In 2000 Aluar installed its first in-house designed launder system for liquid metal transfer from the furnaces to their continuous casting machines. Since then, this type of launder system has been successfully installed in 9 casting lines, both batch and continuous, with flow rates ranging from 2 to 44 tonne/h, for conventional open mould casting, Wagstaff vertical DC billet casting , and Properzi rod casting. The Aluar system is designed to ensure an effective metal temperature control as well as a constant steady “under skin” metal flow, so avoiding turbulence and oxide generation. The highly adaptable system consists of a metal structure, which houses the pre-moulded high durability refractory launders of standardized shapes and dimensions required for the geometry of the desired lay-out: Y shaped, V-shaped, straight, elbowed launders, etc. In this way, the launders enable the connection of the furnaces to the casting machine optimizing the new or existing lay-out, and can be fully integrated to the degasser unit and the filter box without dross generation. The pre-moulded refractory pieces can be easily and quickly removed when their life time is over, thus reducing maintenance costs. Each module is insulated by a thick layer of material to reduce temperature loss (approx. 1°C per m in continuous casting). Another important feature of the system is the thermally insulated heated lids that can be commanded by a PLC to ensure excellent metal temperature control. Efficient launder level control systems ensure an effective achievement of consistent process control parameters. Control flow devices with laser commanded pins allow handling metal height differences up to a range of 200mm, without turbulence. This paper describes the main features of the launder design and presents some case studies in continuous and batch casting lines to show their performance in aluminium alloyed and unalloyed products. Maintenance performance indicators showing typical refractory life time are also included. INFA, an Engineering company of the Aluar group, with a vast experience in engineering works for the aluminium industry, was responsible for the installation and commissioning of these systems and is planning to market this product worldwide in the near future.