HOT METAL PRETREATMENT XỬ LÝ LƯU HUỲNH

HOT METAL PRETREATMENT (De-S) Content: Overview Harmfulness of sulphur Advantages of De-S Hot metal transport Reladling station/pit Methods of De-S: 6.1 Mechanical stirring (KR) 6.2 Powder injection Comparison between KR and powder injection The effect of desulphurization agent Deslagging Overview Harmfulness of sulphur 1) Sulfur deteriorates the property of hot working 2) Sulfur deteriorates tranverse property of steel material 3) Sulfur affects the weld-ability of steel materials 4) Sulfur deteriorates anti-corrosion and conductivity 共晶 體熔 點 FeS 熔點 Hot crack tượng giòn nóng  Sulfur exist in steel with the form FeS 　 lưu huỳnh tồn thép dạng FeS  Melting point of FeS is 1193℃, and it is 985℃ of Fe-FeS eutectic Điểm nóng chảy FeS 1193 ℃, 985℃ pha tinh Fe-FeS  In the liquid phase, the FeS can dissolve in Fe indefinitely; but in the solid phase, the dissolubility of FeS reduces to the value of 0.015%~0.020% pha lỏng, FeS hòa tan vô hạn Fe; pha rắn, độ hòa tan FeS giảm xuống 0.015%~0.020%  When the Sulfur content exceeds 0.020%, the Fe-FeS eutectic will precipitate at the grain boundary during solidification hàm lượng lưu huỳnh vượt 0.02%, pha tinh Fe-FeS kết tủa biên giới hạt suốt trình đông đặc  The hot working temperature of steel is in the range of 1100~1200 oC, the Fe-FeS eutectic will melt at this temperature and cause little cracks in the grain boundaries nhiệt độ cho gia công nóng thép khoảng 1100~1200oC, pha tinh Fe-FeS bị nóng chảy nhiệt độ khiến cho biên giới hạt bị đứt gãy Advantage of Pre De-S ( 預預預預預預 ) 1) Increase the productivity of BF & BOF ( 預預預預預預預預預預預 ) 2) Lower cost ( 預預預預預 , 預預預預預預預預預預預預預預預預預 ) 3) To make steel with high quality ( 預預預預預預預預預預預預預預預預預預預預預預預 ) 4) Enlarge the range of converter making steel ( 預預預預預預預預預預預 ) 5) Smooth produce process & quality ( 預預預預預預預預預預預預預預預預預 )( 預預預預預預 ) 6) Reduce the cycle time for BOF & Refining ( 預預預預預預預預預預預預預預 ) Hot metal transport Torpedo Car ( 預 預預 ) Reladling station/pit Methods of De-S ( 預預預預預 ) - There are two methods to De-S in the hot metal: • Mechanical stirring method ( 預預預預預 ) → FHS using • Powder injection method ( 預預預 ) - The purpose is to reduce the content of sulphur in hot metal: Charging → Stirring → Reaction → Slag → Skimming ( 預預 → 預預 → 預預 → 預 → 預預 ) Lance 預預 Impeller 預預預 Process of pretreatment ( 預預預預 ) 預)  Hot metal initial/final 預 [S] 預 0.035%  0.003% (by SPCO)  Equipment 預 Hot Metal Ladle ( 預預 預) or Torpedo Car ( 預預預 )  Add De-S reagent 預 CaC2, CaO, Mg Traditional ( 預預預預 ) Latest ( 預預預預 ) 10 14 SPCO 15 Running cost  The table shows the relation between initial [S] content and running cost  With increasing initial [S] content, flux consumption increased and therefore running cost increases  However, the running cost is max 1.4 US$/ton 16 Main equipments of KR ( 預預 ) Lifting system Storage hopper Motor Weighing hopper Lifting car Lifting, rotating, and supporting system Fixing system Hood Car is used to replace impeller Hydraulic unit Hot metal ladle 17 Impeller ( 預預預 ) 18 Life time of impeller 19 6.2 Powder injection method - Only use Mg ( 預 ) (Mono-injection): Mg + [S] → MgS(s) - Use CaO and Mg (Co-injection): Mg + CaO + [S] → CaS(s) + MgO(s) - Life time of lance: 100÷120 heats - Treatment time: 29 20 Operation cycle time for powder injection method Lime & Co-injection Carbide/Mg (carbide: 預預預 ) SVAI 21 Main equipments of powder injection 22 Powder injection station 23 Comparison between KR and powder injection SCPO 24 25 The effect of desulfurization agent - CaO is used widely in DeS process because it is cheap and popular - In powder injection method, Co-injection is usually used to desulphurize: high effect and reduce cost 26 Deslagging ( 預預 ) - Remove sulfur which is trapped in the slag - It also maintains clean bath surface without any slag and minimize the iron loss - Main device: Skimmer 27 Slag pot car 28 [...]... Main equipments of KR ( 預預 ) Lifting system Storage hopper Motor Weighing hopper Lifting car Lifting, rotating, and supporting system Fixing system Hood Car is used to replace impeller Hydraulic unit Hot metal ladle 17 Impeller ( 預預預 ) 18 Life time of impeller 19 6.2 Powder injection method - Only use Mg ( 預 ) (Mono-injection): Mg + [S] → MgS(s) - Use CaO and Mg (Co-injection): Mg + CaO + [S] → CaS(s)