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
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/04—Removing impurities by adding a treating agent
  • C21C7/064—Dephosphorising; Desulfurising

Definitions

• Molten ferrous metals may be desulpherized with an additive comprising lime, sodium carbonate, fluorspar [52] US. Cl alone 75/58, 75/53, 75/94 and not more than 025 percent by weight metal chlo- [51] Int. Cl alone-. C21c 7/02 ride.
• ferrous metals includes cast irons, steels and ferro alloys.
• US. Pat. No. 3,537,842 to Holland provides one solution to the difficulty, in the form of a desulphurizing additive comprising lime, iron oxide and an oxidizable metal.
• a desulphurizing additive comprising lime, iron oxide and an oxidizable metal.
• the latter two ingredients react exothermically and this counteracts the loss of heat from the steel which occurs when lime alone is used.
• the additive composition may contain, inter alia, in addition to the foregoing ingredients, a fluoride such as fluorspar to increase the fluidity of theslag.
• a method for desulphurizing molten ferrous metals which comprises adding to the molten metal an additive which is a non-exothermic composition comprising lime, sodium carbonate and fluorspar and which contains at most 0.25 percent by weight metal chloride.
• a non-exothermic composition comprising lime, sodium carbonate and fluorspar and which contains at most 0.25 percent by weight metal chloride.
• the composition is not exothermic.
• the composition may contain other ingredients if desired, these ingredients should not be such as to set up an exothermic reaction.
• the compositions are thus clearly distinguished from those described in British Pat. specification No. I 170168.
• the total of chloride in the composition (calculated as metal chloride) must not exceed 0.25 percent by weight, or fuming during use of the composition becomes excessive. Chlorine tends to be present as chloride impurities in the sodium carbonate used.
• the lime constitutes 40 to 80 percent by weight of the additive.
• the proportions of fluorspar and of sodium carbonate may vary widely but will generally not exceed in either case 50 percent by weight of the composition.
• Preferred compositions are those comprising the specified ingredients in the following relative proportions, by weight:
• a further specific formulation is a composition consisting of: 1
• composition may be in the form of a powder mixture of the ingredients, or granules of the mixture or may be in the form of tablets.
• the invention includes the desulphurizing compositions as defined, and the method of desulphurizing molten steel by adding the said composition thereto.
• molten ferrous metals which includes providing a molten ferrous metal containing sulphur as an impurity and treating said ferrous metal with an additive to form a fluid slag in an amount sufficient to remove sulphur in desulphurizing amounts from said ferrous metal into said fluid slag, the improvement wherein said additive comprises a nonexothermic and non-noxious fume generating composition consisting essentially of, by weight, 45 to 65 parts lime, 10 to 30 parts sodium carbonate, and 25 to 35 parts fluorspar, said additive containing at most 025 percent by weight metal chloride, said composition enhancing said sulphur removal into said fluid slag.
• a nonexothermic and non-noxious fume generating composition consisting essentially of, by weight, 45 to 65 parts lime, 10 to 30 parts sodium carbonate, and 25 to 35 parts fluorspar, said additive containing at most 025 percent by weight metal chloride, said composition enhancing said sulphur removal into said fluid slag.

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)
• Treatment Of Steel In Its Molten State (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=10116805

Family Applications (1)

Country Status (4)

Cited By (7)

Families Citing this family (2)

Citations (3)

• 1970
  • 1970-04-20 GB GB1869370A patent/GB1288872A/en not_active Expired
• 1971
  • 1971-03-24 CA CA108570A patent/CA928081A/en not_active Expired
  • 1971-03-29 US US00129144A patent/US3748121A/en not_active Expired - Lifetime
  • 1971-04-19 DE DE19712118918 patent/DE2118918A1/de active Pending

Patent Citations (3)

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