Technology and equipment for production sponge iron from hematite are fines through Rotary Hearth Furnace has been demonstrated in a setup in China having feed capacity 100,000 Ton per annum. Mean diameter of Furnace is 13.5m. Scale – up of design is ready for 500,000 Ton per annum sponge iron capacity. Low grade Iron ore fines can be utilized, and further processing of produced hot DRI is feasible in electric furnace for desired grades of iron and steel. Coal as reductant is preferable of high grade, whereas lower grades are tolerated.
The methodology envisages cold briquetting of iron ore fines and reductant coal along with limestone/dolomite flux as compared to traditional high temperature agglomeration method. This amounts to lesser investment, easy operation and low input material handling cost and more environmental friendly. In Rotary Hearth Furnace,waste heat of exhaust gas is utilized efficiently by heatup of combustion gasous fuel and combustion air. Dust removal of exhaust gas is in dry bag filter without cosuming fresh water.
Production Line For DRI Sponge Iron has following sectional units :
Specific gravity : 1.8-2.0 Ton/M³
Granularity : < 30mm
Discharge Temperature : 800°C
Cold clean gas (pressurized 15 kPa ) from two-stage coal gasifiers are considered.
Water : Makeup water is required for Cooling water in circulation Furnace seal has separate circulating water being turbid.
Power : Power distribution is to be planned on consideration of further processing of hot DRI in electric furnace for requisite grades of iron/steel.
Production Process and technology for direct production of Sponge Iron from Iron Ore fines without any need of either palletization nor sintering is offered adopted Tunnel kiln and Hematite Iron ore fines. Shape of produced sponge iron is in form of briquette having better density compared to DRI FROM Rotary kiln. Machinery and equipment chosen are up-to-date, reliable, energy saving and environment friendly. Modules are available for 75,000 TPA and 150,000 TPA comprising of three kilns in a group-kiln length is 185m and 260 m in aforesaid module respectively.
Raw material standards :
Iron ore fines : TFe>60%, SiO₂ + Al₂O₃< 7.5%, CaO <2.5%. MgO < 1.5%
Gangue <10%, S< 0.06%,P < 0.06%, Moisture < 10%
Coal : FC > 60%, Volatile < 20%, Ash <10%,Sulpher < 1%,Moisture < 10%,.
Fusion temp. > 1200°C
Limestone : CaO > 50%
Sponge Iron Standards:
For TFe 67%
Sponge Iron Grades : TFe 80-83% 84-86%
With Iron ore finess TFe 61-63% 63-65%
Consumption Norms : Ore fines 1.4 T/T
For TFe 67% Coal 0.45 T/Tcharge
Limestone 0.1 T/T charge
Utilities :Producer gas
Coal 0.65 T/T
Water 0.1 M³/T
Power Load :Size Reduction and Handling, Briquetting,
Tunnel kiln : 2500 Kw ( 75,000 TPA Module )