Such well-developed technologies were applied as serial-type top de alto-forno with central distribution, flat-type cooling stave for hearth, graphite brick for bottom, home-made one-layer carbon block, and dry dedusting. The overhaul covered process, utilities, power supply, drive, automation control, buildings and structures. CISDI was challenged by complicated design and construction and tight schedule. Finally, it experienced 76 days from shutdown to blow-in and tapping, and gained 100% acceptance, working the new record of revamping mega BF in shortest cycle time in China. As it was overhauled, the furnace volume was expanded from 4,350m³ to 4,850m³, and designed campaign life extended from 18 years to 20 years.