A historical perspective of aluminium casthouse furnace developments

摘要

This paper provides an historical perspective of aluminium casthouse furnace evolution over the past 30 years or so with a view towards explaining the reasons for those innovations, and the success or otherwise of some of the changes which were tried. The paper covers electrically energized furnaces such as channel and coreless induction furnaces as well as "glo-bar" heated furnaces. It goes on to discuss fuel fired furnaces including melters of many varieties including side charged, top charged, sidewell, and multichamber designs. Additionally it includes melter/holders and conventional holding (casting furnaces). The drivers for change have been many and varied, and have included the need to cope with capacity creep, reduced specific energy consumption, improved asset utilization, greatly enhanced process intensity, reduced melt loss, improved furnace reliability, acceptance of the benefits of automation, and always the concern for improved safety in all aspects of furnace operation. Accordingly the paper covers related matters such as major changes in burner choices; furnace charging and tending; refractory type and design; furnace enlargement; forced convection stirring; dealing with difficult scraps; the demise of stationary casting furnaces, recognition of the need for improved metal cleanliness; and the challenge to deal with a wider range of difficult alloys. Additionally there has been a much greater understanding of furnace functionality by computer modelling of heat transfer as well as modelling of furnace stress design by FEA as well as some physical modelling and full scale tests to validate computer model assumptions. One of the most significant aspects of improved science has been the manner in which furnaces are operated to maximize productivity, reduce energy cost and melt loss, and by the adoption of purpose built tending vehicles. Finally the paper discusses prospects for future technological development and other aspects of improved productivity through achieving target composition first time as well as by better production planning, together with the aid of dynamic simulation for optimisation of activities.