In July 2001, Dunkirk blast furnace 4 achieved a 13 years and 9 months long campaign with a 41.7 millions tons hot metal cumulative output. The relining works had been scheduled within a 65 to 75 days period for a total cost over 150 millions Euros. The objectives of the next campaign are : a daily production over 10,800 tons, a blast furnace life over 20 years without any intermediate repair, a significant improvement of the working conditions and a major reduction of the environmental impact.

A certain number of changes have been made on the occasion of the relining of blast furnace B at Ghent. They oncern the design of the furnace and the improvement of its cooling system, the repair of the hot blast stoves, the replacement of part of the control equipment and the installation of new measuring devices. Environmental controls and improved working conditions were also at the origin of some changes. The result of this operation is a fine new furnace equipped with the latest measuring and control systems.

CRM developed a probe determining the raw material trajectories in bell-less top charging, by measuring the force generated by the material stream on a beam, in function of its position in the furnace. A prototype probe was tested on an industrial blast furnace during its first charging after a relining. These trials allowed the determination of both coke and sinter trajectories for the various chute angles. These results were validated by measurements carried out simultaneously by Irsid with painted bars.

A new bell-less top was installed at Chiba No.6 blast furnace in 1998 for advanced burden distribution control. Reduced scale model experiments were used to develop the rotating chute with stabilizer and the reverse-forward tilting function. Furthermore, an accurate simulator for burden distribution was developed. The results obtained allowed to implement an operational trial of reverse tilting charging. Burden profile and gas distribution could be controlled satisfactorily with this method.

“Stand-support sintering”, that is supporting the load of the sinter cake with bars or plates attached to pallets, has been developed and applied practically to the sintering machines in Kimitsu works, Nippon Steel. The stands start to support the load of the sinter cake just after the top layer is melted and starts to solidify. Shrinkage is stopped and the gas flow rate is increased when the stands start to support the load of the sinter cake. It was found that sintering time was shortened and productivity was improved in actual sintering machines.

Modern blast furnaces need to be supplied by modern sinter plants. This article presents a series of design and automation solutions for both installations, which not only contribute to an increase of their performances, but also allow to improve sinter and hot metal quality, as well as to optimize operational costs. This is confirmed by the upgrading project examples shown.

The investigation of dioxin formation mechanisms demonstrated that most part of PCDD/F formation occurs in the sinter mix during the sintering operation. This result has a direct impact on abatement strategies of PCDD/F: use ot inhibitors added in the sinter feed and study of the impact of raw materials. Trials carried out on the IRSID pilot pot and on the Charleroi sinter strand have shown that urea addition could be a promising method to reduce pollutant emissions at the sinter strand main stack: PCDD/Fs (about - 50%) and SO2.

A new advanced and breakthrough technology has been developed for hot slab on-line surface inspection and installed in Aceralia (Spain). This innovative inspection system, integrating novel Conoscopic Holography, CCD cameras, a complex mechanical system and intelligent tools, operates in the real environment of a continuous casting facility, allows on-line hot slab surface inspection of 100% of the production, detecting cracks - without removing the surface scale - and inclusions (peeling a narrow strip on the surface).

EISYS is a new optical edge-inspection system for cold rolled strip products. Two cameras examine both cut edges and their indications are used to optimize the edge-trimming conditions without the need of stopping the line or reducing its speed. EISYS has been installed at three different production lines of voestalpine Stahl and has already resulted in significant productivity, quality and cost benefits.

Gas and liquid flow between the various compartments of surface treatment reactors have strong influences on the control of the reactant composition and temperature and, consequently, on the performance of the reactor. Two industrial examples are presented: the tracing of a multi-bath continuous pickling reactor to determine the amount of back mixing and its consequences on productivity, the tracing of multi-compartment annealing reactors to evaluate the gas exchanges between compartments. Mathematical modelling describes the observed behaviours.

Intersittial free (IF) steels used to produce cold rolled sheets are known to be hyper-drawable after recrystallization by continuous annealing. This is reflected by a low proof stress, a high work-hardening coefficient and a high r-value. From an industrial point of view, it is also important now to know how these properties change if annealing does not lead to complete recrystallization.