Slag Granulation Plants

A modern blast furnace can produce more than a million tonnes of slag per year. Efficient processing of blast furnace slag results a product suitable for further use in the cement industry—at minimum emissions and without interrupting operations.

Granulation

The slag granulation system is centered around a high–velocity spray head that quenches molten blast furnace slag, typically flowing at up to 12 tonnes per minute or more. Precisely controlled via a flow–regulating valve and energy balance, the spray head ensures optimal mixing by directing water jets for the slag to flow on. Side jets enhance cooling, droplet formation, and flow propulsion. Detachable nozzle plates with ceramic inserts allow quick replacement, supporting efficient, low–maintenance operation and consistent granulation performance. The water to slag ratio is maintained between 5 and 10 m³/t to produce the correct quality granulated slag. With the Danieli Corus condensation tower, emissions of sulfur compounds are virtually zero.

Dewatering

In the second stage of the system, a rotating dewatering drum separates water from granulated slag. Water drains through perforations or screen panels, while the granulated slag is conveyed forward by the drum’s rotation. This continuous motion, in combination with drum flushing and air purging, ensures efficient dewatering and prevents clogging. The drum’s speed and angle are optimized to balance moisture removal with material flow. The result is a consistently dewatered slag product suitable for storage or further processing, with minimal maintenance and high reliability in demanding ironmaking environments.

Storage

Granulated slag can be conveyed using standard bulk handling systems with belt weighing for continuous measurement. In mild climates, the granulated slag may be stored in simple stockpiles—for further, natural dewatering over time—or in vertical hoppers with lock–hopper discharge. Stockpiles can be sized for daytime–only reclaiming. Due to its chemical stability, slag drainage water is typically free of contaminants.

Sustainable slag handling

Efficient blast furnace slag granulation contributes to low cost hot metal. The Danieli Corus slag granulation system has the following benefits:

• Simple plant configuration with few moving components
• No heavy crushing equipment is required
• The specially designed spray head produces a uniform grain size (up to 3 mm)
• Adjustable spray head produces slag sand with more than 98 glass content
• Condensation tower eliminates H₂S and SO₂ emissions
• Efficient cooling tower eliminates sand deposits and clogging
• High availability (> 98 %) and low maintenance due to the above