Cold start

is the starting of a crucible following a shut-down. In an NF furnace, starter blocks are required reaching up to 2/3 of the coil height. These blocks are heat- ed inductively and then settle together. At this point, small quantities of scrap can be recharged. After reaching the 2/3 filling level, larger quantities of scrap can be added (5% of the total capacity) and melted. The furnace is brought up to the maximum filling level at approx. 70% of nominal performance. The melt should now be brought up to about 100 K below the normal tapping tempera- ture, and maintained at this temperature for 1 hour. The furnace is then brought up to tapping temperature and the 1st tapping carried out.