Ladle filler sand (Nozzle Sand)
Ladle filler sand is a mixture of refractory raw materials and it is filled in nozzle of sliding gate systems. Main purpose is to achieve a high natural opening rate, avoiding the clogging when the sliding gate is opened. Most important factor is that sinter layer is formed where the contact surface between molten steel and the upside of ladle filler sand.
Nozzle sand in a ladle tap hole is to prevent molten steel from solidifying within a nozzle slide gate or to the rotary nozzle.
When the slide gate is opened the nozzle sand falls out freely, creating an opening by itself, or a free opening, through which the molten steel flows down.
Graphite or other additives are added to help prevent sintering, and makes the nozzle sand less wettable by molten steel.