Steel slag is a steel-making industry by-product, currently used forseveral applications in substitution of non-renewable natural resources(e.g., crushed stone and sand). The major reason for conductingthis study at CST ArcelorMittal Brasil was to verify if any of the currentuses of LD and NP slag presented significant risks to the environmentand/or human health.

At the present time roll shops are characterized by increasing automationand faster production cycles. Automatic quality inspection oftechnical processes as a part of quality management becomes evermore important. The integration of an inspection system within theautomatic program cycle of a roll grinder and the fast feedback ofthe inspection results lead to decreased scrap rates and advancedproduct qualities. On this account WALDRICH SIEGEN has developedthe new Roll Surface Inspection System RSIS.

The high sensitivity of the local community to the dust issue led usto develop a continuous monitoring of dust deposits in the surroundingsof the Dunkerque plant. These measurements are most accuratelyexploited with a new tool that has been developed to alert andto analyze the strong dust deposits. This information makes it possibleto identify the sources of emission that originate the dust depositsand to take appropriate measures to reduce their impact.

Hot tearing close to the solidus temperature occurs in continuouscasting of steels. Four hot tearing criteria from the literature are reviewedand assessed against laboratory tests. Based on a critical straincriterion, an accumulated strain approach is introduced and criticalvalues are determined by laboratory experiments.

Oil layer and surface roughness of steel strip are measured on-linewith equipment that has been adapted to withstand the severe environmentof a cold rolling mill. The system ensures the effective lubricationof the strip and it displays roughness data all along the coil.This makes it possible to optimize the rolling process on-line and itaffords comprehensive information on the strip properties.

During 2006 four chilled blast furnaces were recovered using theoxyfuel lance technology. All recoveries were successful andbrought the blast furnace back to full production within 200 hours.This recovery method has been under constant development since1990 and has now been applied over 25 times. It is considered safer,faster, easier and cleaner than the traditional recovery methods forchilled hearths.

In December 2003, Rasselstein GmbH Germany placed an orderwith the consortium VAI (Consortium leader) and Drever (Furnace)for the erection of the new continuous annealing line n° 5. The constructionof this annealing line takes place in a new building simultaneouslywith the construction of the tinning line n° 12. This modernline is unique in that for the first time it is planned to homogeneouslyanneal strips in widths from 800 to 1,400 mm. The future capacityamounts to 360,000 t. After annealing and finishing rolling thematerial is coated in a tinning line after which it finds use as an intermediateproduct for the beverage and packing industries.

The Clean Development Mechanism Project elaboration is reviewed,considering every step from the project design document conception,through validation, the approval by the national authorities andthe verification process.The whole development is pioneered by CST ArcelorMittal Brasil,aiming at carbon credits generation and GHG emission reduction.An associated objective is the promotion of sustainable development.The potential of carbon credits generation is estimated to be440,263 tons of CO2 over a CDM project period of 10 years.

The development and implementation of a prototype to improve thecurrent maintenance procedure applied to the SIS, SafetyInstrumented System, of the raw materials and products conveyorbelts of the Coke Plant operational unit of CST are reported. Due tothe continuous mode of operation, currently protection switches canonly be inspected visually, which does not ensure a perfect operation.The aim of this new tool is to allow the online inspection andtesting of the safety switches without interfering with the productionand to maintain its functionalities.

The Carinox production facility comprises a 160 ton EAF, a 180 tonconverter, a twin 180 ton stand ladle treatment station, a singlestrand slab caster, auxiliary plants and the dedusting and automationsystem. This article outlines the principal features of this successfulproject.

EAF, with power ratings over 100 MVA, cause voltage fluctuationsand flicker in the supplying power system. Static VAr compensators(SVC) are typically used for reactive power compensation. Thispaper presents a solution for how to obtain an optimum flickerreduction at a comparatively low compensator power rating. Theresearched compensator solution represents an optimum from thetechnical as well as from the economic point of view.

New dynamic features of the descaling process are reported, referringto the continuous water jet formed by the descaling nozzle in particular.A water jet is formed by clusters of droplets moving at highvelocity. In the impact area, pressure peaks of several hundred MPa,lasting microseconds per peak are observed: this is described as the“water hammer” effect. This finding modifies most existing conceptsof descaling and the impact on current theory is discussed.

A modelling strategy has been developed to reduce the overspreadat the finisher of the HSM in Avilés. A new hybrid data based modelelaborates the roughing and finishing mills set up. It has made it possibleto reduce the overspread by 1.5 mm at the finisher since March2005. The model is modular and flexible and it can be transferred toother installations.

The influence of the flow phenomenon of the cooling nozzle affecting the rod temperature and the factors affecting the cooling efficiency were examined through experiments and numerical analysis. The optimal conditions featuring excellent cooling efficiency can be deduced in the future by analyzing the flow conditions and design conditions.

The repair of a walking beam furnace is usually achieved by replacingthe damage block or by gunning a wet refractory mix on the hotsurface. A new alternative is introduced, based on the ceramic weldingtechnology. It has been successfully applied by Industeel intheir slab reheating furnaces.

The meniscograph and the sessile drop wetting methods, associatedwith in situ surface analyses, were used to quantify the influenceof the annealing atmosphere on zinc wetting during the hot dipgalvanising of high strength steels. If a clear wetting improvement isobtained for higher oxygen partial pressures, associated with a sufficienthydrogen amount, in the soaking area, a dry atmosphereabove the zinc bath has however to be preferred.

Dross growing on immersed rolls is responsible for defects on thegalvanised strip. It is essential to identify the mechanism of thisaccumulation on immersed hardware. An industrial approach hasbeen followed: stainless steel samples (316L) were set up at severallocations on the moving rolls and on the static members through agalvanising campaign. The samples were then analysed by means ofoptical and electron microscopy. The results from this first approachpointed out significant effects of some factors referred to as “location” and “moving”. Further investigations, including a deeper analysisof several parameters, are requested to validate the proposedmechanisms.

The feasibility of direct thin strip casting of various steel grades forfurther metallic coating has been investigated. The surface evolutionis described for each processing step. Special attention to steelcleanliness and scale formation was given, since local surfaceheterogeneities of grain structure and chemical composition maydisturb the coating process. Low alloyed cast strip can be coatedwith little to none difference to classical coating routes, however,some highly alloyed steel grades require further optimization.

The application of flameless oxidation to steel batch furnaces isreported. Transient heat transfers have been assessed through amixed CFD and zone model approach. This makes it possible toimprove the heat transfer in industrial furnaces and to reduce theenergy consumption.

To answer the current demand for hot dip galvanized automotive products, ArcelorMittal decided to modify its Mardyck electrolytic galvanizing line. Compared to the construction of a new hot dip galvanized facility, this option affords the advantage of re-using the entry and exit sections of the existing electrolytic line, as well as the building. The annealing furnace, supplied by Stein Heurtey, with amaximum capacity of 85 t/hr, was commissioned at the end of 2005.