For years, the iron and steel industry has been in search of new processes for an efficient production of virgin steel as well as for the recycling of its by-products, especially for those containing zinc. Considering these objectives, Paul Wurth S.A., in cooperation with ProfilARBED, has developed a process using the multiple-hearth furnace and coal fines as the reductant and main energy source. A trial plant with a capacity of 2 t/h was built and has been operated for more than one year at the ProfilARBED Belval site. This paper reports on the trial campaigns, which have given most promising results.

The optimized overall control system developed by VAI for sinter plants integrates mathematical models and artificial intelligence. It features a process information system and a collection of on-line process models. One group of models is used for the control of sinter productivity and the other group for the control of sinter quality. The setpoints calculated in that way control the sinter plant operation directly. The different modules included in the system are described in the case of the Wuhan Iron and Steel Co. sinter plant in China.

The initial solidification in the continuous casting process can be controlled by imposing a pulsative AC electromagnetic field on the meniscus. The casting experiment of a steel billet has been conducted by using a commercial billet caster. The imposition of a pulsative AC electromagnetic field has greatly improved the surface qualities. This presentation provides the results of the electromagnetic casting project of JRCM which is supported financially by the Ministry of International Trade and Industry of Japan.

In the context of the development of a new concept of electromagnetic continuous casting of slabs, in which an alternating magnetic field (AC) with middle range frequency is combined with a continuous magnetic field (DC) in the vicinity of the mould meniscus, the study carried out by Irsid and EPM Madylam made it possible to develop numerical simulations for both the alternating and continuous magnetic fields. The calculations have been developed for the middle frequency range of alternating fields. They made it possible to correctly describe the average deformation of the free surface and the recirculation speed patterns in various AC configurations, as well as a good prediction of the damping effect of the DC magnetic field on the recirculation speed of liquid steel and the modification of the free surface deformation.

An experiment of continuous casting with ultra-high frequency electromagnetic field was carried out at No. 4 commercial caster at Kobe Works. It was confirmed that the durability of a slit mould was sufficient for long casting, and meniscus level was controlled precisely enough for stable casting by the level control technology using the inductance change in the magnetic system. The improvement of billet surface quality and the lubrication between the mould and the solidified shell are discussed.

To reduce roll wear and chatter vibrations in its hot strip mill, Eko Stahl carried out roll gap lubrication trials. The trial equipment, the lubricant and the trials themselves are described. Rolling force and consequently electric energy consumption were reduced by 8 to 34 % . The automation system reacted without difficulties to sudden rolling force changes. Three types of torque changes due to roll gap lubrication have been observed. Chatter vibrations have been suppressed efficiently during lubrication. Roll wear decreased. Strip thickness and profile tolerances were affected positively, other quality parameters did not change significantly.

An efficient way to increase the operational performance of hot strip mills is to lubricate the work rolls. A series of tests have been carried out at the hot rolling mill of Chertal (Cockerill-Sambre - Usinor). The main benefits which have been observed when using lubrication concern the reduction of friction and of rolling force.