NEW CHARGE MATERIAL FOR BLAST FURNACE

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NEW CHARGE MATERIAL FOR BLAST FURNACE

Yogesh Dalmia (speaker) General Manager of Suraj Products Ltd, India)Ivan Kurunov (Novolipetsk Steel, Russia),Richard Steele and Aitber Bizhanov (J.C. Steele & Sons, Inc, USA)

NEW CHARGE MATERIAL FOR BLAST FURNACE

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CONTENS:

1. Stiff Extrusion as a New Technology for Metallurgical Waist Briquetting

2. Ironmaking plant “Suraj Products Ltd” in Rourkela (India)  

3. Components of the charge for briquettes production 

4.Technology of briquetting by stiff extrusion 

5. Composition and metallurgical properties of Brex  

6. Blast Furnaces at the Company “Suraj Products Ltd” 

7. Technical-economical parameters of the Blast Furnace operation with Brex in charge  

8. Conclusion

NEW CHARGE MATERIAL FOR BLAST FURNACE

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Stiff Extrusion as a New Technology for Metallurgical Wastes Briquetting

In 1993 at the Bethlehem Steel Corporation plant (USA) the first industrial line for production the briquettes from the metallurgical wastes based on the stiff-extrusion technology had started The first Brex making line had been realized on the equipment produced “ by J.C.Steele & Sons” company. The productivity of the line was 20 t/hour. The Brex were produced from the BF sludge and dust. The Portland cement and the lignin were used as the binder and plasticizer. The Brex were used in the Blast Furnace charge. The line had been in a continuous operation till 1996 when the main production of the Steel plant had been cancelled.

NEW CHARGE MATERIAL FOR BLAST FURNACE

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Metallurgical plant “Suraj Products Ltd” in Rourkela (India).

Utilization of the new briquetting technology has been renewed only at present time. In April 2011 the industrial line for the production of the Brex from waste has been launched at the «Suraj Products Ltd» company metallurgical plant in Rourkela (India). The plant produces hot metal by two small-scale Blast Furnaces and the sponge iron by the kilns. Briquetting line includes: warehouse of the raw-materials; unit of the charge preparation (dosing, grinding, stockpiling, hopper feeding); mixing and briquetting unit; line of the transportation of the Brex to the strengthening area; ready Brex warehouse.

NEW CHARGE MATERIAL FOR BLAST FURNACE

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Components of the charge for briquettes production and technology of briquetting by stiff extrusion

The components of the Brex are: BOF and BF sludge and dust (66 %), iron ore (28 %), the Portland cement and plasticizer (6%). The volumetric dosing is being implemented by the auto loader, which creates the stockpile of the charge mix (without the cement), taking each component from separate stockpiles. Charge mix is also being fed to the hopper of the briquetting line by loader where from it goes through the homogenizing mixers to the extruder. Due to the applied pressure during extrusion and the de-airing of the mix (90%) in the vacuum chamber the Brex do have a dense structure at the die exit, high initial strength and a good plasticity. This helps to transport and to stockpile the Brex without fines generation.

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During the transfers only the defragmentation of the Brex into 2-3 pieces takes place with the creation of the Brex with the length/diameter ration being 1,3-2,2 while this value after the die was in the range of 2,5-8,0. Simultaneously a small turning of the Brex sharp borders takes place. For the strengthening the Brex are being cured in the stock at the open place. 

NEW CHARGE MATERIAL FOR BLAST FURNACE

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Composition and metallurgical properties of brex at “Suraj Products Ltd”

Mechanical strength measurement of the ready Brex has show very good compressive strength values (100-130 kgF/cm2). Fine output from Brex during their transit and handling was not more 5 %.

Fetotal CaO %; SiO2 Al2O3 MgO H2Ohyd +C СаО/SiO2

46-48 10-11 7.2-7.7 1.7-1.9 2.7-2.9 11-12 1.39-1.42

Chemical composition of the Brex after curing:

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Hot strength of the sludge Brex ( BF sluge 60 %, BOF sludge 40 %), iron ore-coke Brex (concentrate -85 %, coke breeze – 15%) and agglomerates have estimated in accordance with ISO 4696 Standard based on the standard equipment. The following RDI (-3,15) and RDI (+6,4) values have been received:

Tested materials RDI (-3,15), % RDI (+6,4), %

Iron ore-coke Brex 38 62

Sludge Brex 3,5 96,5

Agglomerate (basicity 1,2) 16,9 64

Agglomerate (basicity 1,4) 15,1 60

Agglomerate (basicity 1,6) 8,9 77

On can see that hot strength of Brex is not bad

NEW CHARGE MATERIAL FOR BLAST FURNACE

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Blast Furnaces at the Company “Suraj Products Ltd”

Blast Furnaces at the Company “Suraj Products Ltd” plant (volume 45 m3 and 25 m3) are equipped by: skip hoist with the volume 0,5m3, double-cone charging device, and hydraulic equipment for the notch servicing, stoves and dry gas-cleaning system (dust collector + 7 modules of the bag house filters). The furnace has 8 air tuyeres, one hot metal notch and is being cooled by external watering. Produced hot iron is immediately casted by the casting machine and the slag is granulated near to the furnace.

NEW CHARGE MATERIAL FOR BLAST FURNACE

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Technical-economical parameters of the Blast Furnace operation with Brex in charge

The efficiency of the utilization of the Brex can be seen after the comparison of the operation parameters of the Blast Furnace working on the iron ore and on the charge with 80% of the Brex and 20 % of the iron ore.

Parameters of the Blast Furnace operation With iron ore With Brex

Iron ore consumption, kg/t 1500 372Brex consumption, kg/t - 1444Lime+ Dolomite consumption, kg/t 294 -Scrap consumption, kg/t 132 -Fe content in fluxed charge *,% 57.6 50.4Coke rate, kg/t 680 530Productivity, t/m2 per day 1.9 1.62Hot blast temperature, ºС 925 900Tuyere pressure, kg/cm2 0.5 0.36Hot metal chemical composition, % : Si 1.4 1.25 Mn 0.2 0.45 S 0.055 0.044Slag basicity 1.09 1.1

Note: * - not accounted for СО2 carbonates.

Technical-economical parameters of the Blast Furnace operation

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One can see that the coke rate after using the charge with Brex (80%) and the iron ore (20 %) decreased by 150 kg/t of hot metal (22%) as a result of the consumption of the carbon containing Brex as well as due to the removal of the raw fluxes from the charge. Reduction in the productivity of the Blast Furnace by 15 % with this new charge with Brex is mainly related with the decrease in Fe content in such charge - 7,2 % compared with the charge based on iron ore and the raw fluxes. The further growth of the Brex share in the charge was restricted by the growth of the basicity of the slag due to the high basicity of the Brex containing the BOF sludge.

680

530

57,650,41,9 1,62

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The equipment and the technology of the stiff-extrusion make it possible to produce the Brex having high strength and reducibility. Metallurgical properties of the Brex allow using them successfully in the Blast Furnace melting. Utilization of the sludge Brex with the basicity 1,4 in the small-scale Blast Furnace at the level of 80% of the charge (1444 kg/t of hot metal) helped to reject entirely from the introduction of the lime and dolomite and to reduce the coke rate by 150 kg/t of hot metal. 

Conclusion