Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C1/00—Refining of pig-iron; Cast iron
  • C21C1/02—Dephosphorising or desulfurising
  • C21C1/025—Agents used for dephosphorising or desulfurising

Definitions

• the invention relates to an agent for the desulfurization of pig iron.
• hot metal or steel can be desulfurized by adding quicklime to the molten iron.
• quicklime for example, when steel is being produced in the oxygen inflation converter, lime is added to bind sulfur.
• the object of the invention is therefore to provide a highly effective desulfurization agent which can be introduced into the pig iron to be treated with a smaller amount of conveying gas and thus enables less material losses and considerable energy savings through less cooling of the pig iron to be desulfurized.
• the agent according to the invention is preferably in powder form, which is obtained by grinding the components.
• the agent according to the invention preferably has a particle size suitable for pneumatic conveying.
• the diamide lime used as a component of the agent according to the invention is a chemically produced, precipitated calcium carbonate which has a carbon content of 5-40% by weight.
• the desulfurization agent according to the invention with a diamide lime content of about 40% by weight is particularly suitable for hot metal desulfurization in torpedo ladles.
• the desulfurizing agent according to the invention preferably has a diamide lime content of 15-25% by weight.
• the diamide lime contained in the desulfurization agent according to the invention has a carbon content of 5-50% by weight and preferably 10-40% by weight.
• the desulfurization agent according to the invention may further contain minor additions of conventional auxiliaries, for example a fluorspar content of up to 10% by weight.
• the desulfurizing agent according to the invention requires a significantly smaller amount of conveying gas than the quicklime used up to now for the same purpose.
• the agent according to the invention can be conveyed uniformly with a conveying gas amount of only 7 N1 per kg.
• the calcium carbonate portion of the diamide lime decomposes abruptly after it emerges from the lance through which the agent is introduced into the pig iron to be desulfurized, thereby ensuring intensive mixing of the solid desulfurizing agent with the iron melt to be treated.
• the calcium carbonate portion of the diamide lime initially becomes more reactive because freshly burned lime (CaO).
• the desulfurization agent according to the invention has the considerable advantage of a substantially improved reactivity compared to the lime used conventionally.
• the agent according to the invention which had been prepared by grinding 60% by weight of quicklime and 40% by weight of diamide lime with a carbon content of 20% by weight, was then used in the same plant to desulfurize the same pig iron.
• To achieve the same desulfurization effect only 4.8 kg of the desulfurization agent per ton of pig iron were required.
• the mixture could be pumped with little gas.
• For uniform, trouble-free blowing only 7 N1 of conveying gas per kg of the desulfurizing agent were necessary.
• the conveyor speed could therefore be increased to 100 kg per minute. Even at this higher blowing rate, only 700 N1 of conveying gas per minute were required. This corresponds to only about a fifth of the amount per unit of time for the promotion of the burnt lime was necessary. This resulted in a correspondingly lower turbulence of the melt.
• the pan was well filled, no ejection occurred.
• Another advantage of the desulphurizing agent according to the invention which can only be used in a smaller amount, and the possible higher conveying speed, is that the treatment of the 160 t of pig iron was finished after about 10 minutes, while the desulphurization treatment with quicklime lasts practically 1 hour. Such a long time is normally not available for desulfurization. A consequence of the lengthy treatment using large amounts when blowing in quicklime is still a strong cooling of the pig iron melt. For example, the temperature of the hot metal that was desulfurized with quicklime decreased by 42 ° C, while the temperature loss when using the desulfurization agent according to the invention was only 8 ° C.
• the desulfurizing agent according to the invention has surprising advantages over the commonly used quicklime.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Filtering Of Dispersed Particles In Gases (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Tea And Coffee (AREA)
• Soy Sauces And Products Related Thereto (AREA)
• Fats And Perfumes (AREA)
• Catalysts (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6100415

Family Applications (1)

Country Status (6)

Cited By (2)

Families Citing this family (6)

Citations (1)

• 1980
  • 1980-04-18 DE DE3015024A patent/DE3015024C2/de not_active Expired
• 1981
  • 1981-02-24 CA CA000371607A patent/CA1171663A/fr not_active Expired
  • 1981-03-10 EP EP81101765A patent/EP0038417B1/fr not_active Expired
  • 1981-03-10 DE DE8181101765T patent/DE3167539D1/de not_active Expired
  • 1981-03-10 AT AT81101765T patent/ATE10650T1/de not_active IP Right Cessation
  • 1981-04-07 ES ES501153A patent/ES501153A0/es active Granted
  • 1981-04-14 JP JP5518581A patent/JPS56158807A/ja active Pending

Patent Citations (1)

Non-Patent Citations (2)

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