The challenge

During history of steel production theprocess of continuous casting became moreand more important since the 1960s. Todaymore than 80% of the worldwide steelproduction uses continuous casting. In somecountries, e.g. Germany, the amount isbigger than 95%.

To maximize production output it is essentialto optimize operational and maintenanceflexibility of the caster ongoing. Beneathmachine elements and control systems thisconcerns the secondary cooling as well.

Scheme of continuous caster:

Below the mold the slabs have to be cooledby spraying cooling water until its completesolidification.

Crucial for an effective spraying is including:

• drop velocity
• drop size
• water drop fluxIt

It is obvious that clean and free of scale spraynozzles are unalterable for an efficient and precisecooling of the slabs. An improper spray patterncould not only cause cracks but decrease steelquality significantly. Main source for cloggingissues at the spray nozzles is calcium fluoride.

Spray nozzles with initial calcium fluoride scale:

The solution

To avoid scaling and clogging Kurita uses specialcrystallization inhibitors. Through the adsorption ofinhibitor molecules on selected crystal faces, achange in the morphology of the developing scalecrystals can reduce the rate of crystallization tonearly zero.

The LD-steel plant of this study uses products ofthe Kurita Polycrin series very successfully.