The steel belt sintering furnace has brought smelting furnace efficiencies to a whole new level. By utilizing sintered pellets, furnace operations are more stable and profitable.
Pelletizing and sintering play a crucial role in modifying the smelting behaviour of ore, as good ore uniformity results in consistent furnace performance, lower power costs and higher recovery yields. Outotec’s pelletizing and sintering concept is energy-efficient and uses raw materials effectively. Plant dust from dust extraction is recycled and all reaction gases are circulated for maximum heat energy.
The main raw materials in the steel belt sintering process of chromite are concentrates and/or ore fines plus fine coke. These feed materials are ground in a ball mill, dewatered in capillary-effect ceramic filters, pelletized in a drum and finally sintered in the SBS™ furnace. The end product of the SBS™ furnace is spherical, uniformly sized, hard and porous chromite pellets with consistent physical and chemical properties. They are ideal charging material for ferrochrome smelting in the submerged arc furnace. The utilization of CO-rich off-gas from the SAF furnace can further increase total savings.
Advantages of pelletizing and sintering
The advantages achieved by implementing the pelletizing and sintering process include:
- High environmental limits can be achieved with smaller gas cleaning units and efficient recycling of cooling gases;
- Low operational costs;
- Good and very consistent pellet quality;
- Pellets can withstand long transportation distances due to their high strength and they can also be sold for other uses.
Outotec’s pelletizing and sintering concept is energy-efficient and uses raw materials effectively. Plant dust from dust extraction is recycled and all reaction gases are circulated for maximum heat energy.
Technical specifications for chromite sintering furnaces
- Design capacity 100 000 – 700 000 tpa
- Total length 20 – 50 m
- Belt width 3 – 6 m
- External energy consumption 150 – 250 kWh/t
- Total electric energy consumption in pelletizing plant 45 – 80 kWh/t product
- Green pellet feed 15 – 100 t/h
- Temperature inside furnace 1250 –1500 °C
- Exhaust gas total 50 000 – 250 000 Nm3/h
- Cooling air total 50 000 - 250 000 Nm3/h
- Sintered product pellet 12 – 90 t/h
The most profitable ferrochrome production concept
The enclosed structure of the Outotec® Ferrochrome Process and modern automated control systems give high availability and reliable operation as well as a clean working environment. Emission levels from the sintering and smelting plants comply with all environmental standards. Low energy consumption, small process gas volumes, which are circulated for maximum heat energy recovery, and closed process water circulation also make the Outotec ferrochrome process attractive from an environmental point of view.
Benefits of using high quality pellets for ferrochrome smelting:
- Enables use of low cost chromite fines
- Increases production in existing furnaces
- Furnace can be closed and utilize CO gas and preheating in OPK™
- Enables bigger production units
- Smaller unit costs