December 2011 - SIMA

More documents

Recommendations

Info

AVERAGE PERFORMANCE PARAMETERS:Sl. No. Parameters Trial Heats with Pellets Base Heat with Iron ore DRI1 % Yield of liquid metal 84.45 86.042 Heat duration (Hrs.) 3.20 2.953 Specific Power Consumption(KWH/MT) 863.23 846.944 Heat Wt. (MT) 11.31 11.525 Slag Charactics Very thick Foamy6 % Plant availability 92.09 97.46PROBLEMS FACED:-It is obvious from above data that A grade Pelletcharging resulted in following constraints:(i)Slag was very thick and it was not foamy.(ii) % Yield came down due to metal loss in slag andless Fe content.(iii) Heat duration increased due to problem in slagremoval.(iv) Specific power consumption increased due toprolonged heat duration and less yield.(V) Slag volume was more.INVESTIGATIONS TO ASSESS THE ASSIGNABLE CAUSES:In order to find out the reasons for above constraints, detailed analysis of iron ore based and Pellet based DRIwas done and found to be as follow:S.No Iron ore based DRI Pellets based DRI% % % % % % % %Fe(M) Fe(T) Metallization FeO Grade Fe(M) Fe(T) Metallization FeO Grade1 84.18 92.11 91.39 10.23 A 84.38 88.34 95.51 5.11 A2 83.09 91.88 90.43 11.34 A 83.33 88.13 94.55 6.19 A3 82.49 91.75 89.91 11.94 A 82.08 87.88 93.40 7.48 A4 81.50 91.54 89.03 12.95 A 80.21 87.51 91.66 9.42 A5 80.89 91.42 88.48 13.58 A 79.82 87.43 91.29 9.81 B6 80.46 91.33 88.10 14.02 A 77.95 87.05 89.54 11.73 B7 77.31 90.66 85.27 17.22 B 77.52 86.96 89.14 12.18 B8 76.03 90.40 84.10 18.54 B 76.82 86.82 88.48 12.90 B9 75.50 90.28 83.62 19.06 C 76.11 86.68 87.80 13.63 B10 64.34 87.94 73.16 30.44 C 75.23 86.50 86.97 14.54 CDECEMBER-<strong>2011</strong>/18
Above data are shown graphically also in figure - 3:It is clearly evident from above data and the graphthat % metallization is comparatively higher by about4-5% in case of DRI Pellets for the same Fe(M)contents. This higher metallization resulted in lowerFeO content of Pellet based DRI compared to ironore based DRI as shown below:(i)Iron ore based DRI = 10.23 – 14.02 % FeO in Agrade.(ii) Pellet based DRIgrade.Fig.-3= 5.19 – 9.42 % FeO in ANormally A grade DRI having metallization of 88-92%is used in steel making for smooth furnace operation.But with A grade DRI Pellets lower FeO contentresulted in inadequate boiling and hence, dense slag,causing difficulty in its removal and other relatedproblems as mentioned above.CORRECTIVE MEASURES:As there is no Oxygen injection in induction furnaces,some measures were taken to feed extra FeOthrough some additives in the furnaces as indicatedbelow:a) MILL SCALE ADDITION:As mill scale contains high FeO, the same was addedin the furnaces when slag was getting jammed, but itwas not found to be very effective. It is felt that millscale gets lost in the slag, as it is a very fine material.b) IRON ORE ADDITION:Attempts were also made to charge sized Iron ore inthe furnaces in place of mill scale but its effect wasfound to be very slow in the furnaces. Hence it wasdiscarded.c) ADDITION OF ABOUT 10 - 15% B GRADESPONGE IRON IN CHARGE – MIX:With B grade S.I. [76%> Fe(M) < 80% ] charge mixcomposition was changed as follows:A grade DRI Pellets = 80 - 85%B grade sponge iron = 10 - 15% (approx.)Scrap = 5%It was observed that furnace operation was smoothwith the above charge mix composition. Problems ofslag jamming, high heat duration & excessive powerconsumption were resolved by this measure. Thereafter it has been put to regular practice in our plant.QUALITY OF STEEL OUTCOME:Output steel quality of induction furnaces is a matterof concern as silica lined induction furnaces areunable to carry out any refining operation. They arepresently treated as merely melting furnaces. So bothde-phosphorization and desulphurization cannot becarried out in induction furnaces. Though Sulphur canbe reduced by installation of LRF but, the processfor Phos removal is always difficult although undercontinuous development through IRF (InductionRefining Furnace) as claimed by M/s. Electrotherm.In EAF Phos and Sulphur can be controlled by makingoxidizing and reducing slag practice as well as byoxygen blowing.However Monnet manages to produce quality mildsteel billets and finished structural steel sections bycontrolling raw material quality strictly to maintain anaverage quality range as achieved with DRI Pelletsis as follows:%C %Mn %S %P %Si0.12-0.25 0.50-0.80 0.040-0.045 0.050-0.060 0.15-0.35DECEMBER-<strong>2011</strong>/19
Page 3 and 4: CHAIRMAN’S MESSAGEI am happy that
Page 5 and 6: Target Setting:The methodology for
Page 7 and 8: Energy conservation Opportunities i
Page 9 and 10: MXCOL ® : A BREAKTHROUGH IN COAL-B
Page 11 and 12: MIDREX ® Direct Reduction PlantThe
Page 14 and 15: IRON ORE PELLETS AS THE FUTURE META
Page 16 and 17: Raw material availability:Basic raw
Page 18 and 19: ore also could be intended to gener
Page 22 and 23: CONCLUSION:The salient features of
Page 24 and 25: HARI MACHINES JOINS HANDS WITH RAFA
Page 26 and 27: Indian Reference of RafakoSA - Pola
Page 28 and 29: DECEMBER-2011/26
Page 30 and 31: e maintained while taking advantage
Page 32 and 33: Plant Upgrades Reference ListPlant
Page 34 and 35: TRI-FLO ® :-THE NEW GENERATION MUL
Page 36 and 37: The ability of the Tri-Flo ® to be
Page 38 and 39: Rejects re-cleaning with a 700 mm I
Page 40 and 41: GREEN FIELD STEEL PROJECT OF JSPLJS
Page 42: DECEMBER-2011/40

December 2011 - SIMA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?