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
• • 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
  • C21C7/0645—Agents used for dephosphorising or desulfurising

Definitions

• the present invention relates to a process for the production of desulfurization agents based on calcium oxide-containing calcium carbide for pig iron or steel melts.
• a calcium carbide-calcium oxide melt mixture with a CaO content of 20 to 80% by weight is first produced from lime and coke, which is allowed to solidify to form a block. While the solidified block still has an average temperature of more than 400 ° C, it is broken down to a grain size of less than 150 mm and calcium oxide is added to the crushed mixture, which is still at least 400 ° C, in such an amount that it can be found in the The resulting total CaO content corresponds to the desired CaO content in the end product.
• the mixture is then ground with intensive mixing and exclusion of moisture at temperatures above 100 ° C to grain sizes smaller than 10 mm.
• the finely divided lime was preferably introduced into the jet of carbide tapped from the furnace. Although the amount of lime that can be introduced into the molten carbide is limited and working with liquid carbide is associated with dangers, it was previously believed in specialist circles that this method could not be dispensed with because it was believed that only a mixture of CaC produced in the melt 2 and CaO are best suited for the desulfurization of metal melts.
• Desulphurization agents based on calcium carbide which contain substances which release water at the temperature of the molten metal, are already known from DE-B2-22 52 795.
• These agents which are mixtures of commercially available carbide with, for example, Ca (OHh as a water-releasing substance, have the disadvantage that they are mixtures produced by mechanical mixing, in which carbide particles are present separately from Ca (OH) 2 particles, which is the case when these products are used leads to a higher consumption, uneven and violent gas reactions and a large spread regarding the desulfurization effect, which makes a targeted use of these agents difficult.
• the mixture is then mixed vigorously and in the presence of air or nitrogen with a moisture content of 5 to 20 g / m 3 (at 1.013 bar and 273.15 K) at temperatures below 100 ° C., preferably at 10-15 ° C. , ground to grain sizes less than 10 mm, preferably less than 100 1 1m.
• a calcium carbide-calcium oxide starting melt mixture with a CaO content of 20 to 45% by weight which was obtained in a known manner from lime and coke in a thermal manner.
• a calcium carbide-calcium oxide starting melt mixture with a CaO content of over 45 to 80% by weight is first produced by adding finely divided calcium oxide to an existing calcium carbide melt which has a calcium oxide content of up to 45% by weight to a CaO content of up to 80% by weight and only then solidify the whole into a block before breaking it at temperatures above 400 ° C.
• the method according to the invention also has the further advantages, inter alia, that a certain Möller composition is not set in each case to produce the carbide melt, and that the lime does not previously have a specific grain size must be finely ground, but that it can be assumed that a carbide block whose CaC 2 : CaO weight ratio fluctuates within a very wide range, that is to say can be practically arbitrary, and the lime also in coarse-grained form, for example in a grain size between 8 and 60 mm, can be used.
• a further advantage of the inventive agent prepared is that densely present on the surface of each grain Ca (OH) 2 addition CaC 2, is set very early and uniformly in motion whereby the desulfurizing reaction. As a result, ver Similar desulfurization results require smaller amounts of the desulfurization agent and enables more targeted results.
• a carbide block of corresponding composition was produced in a crucible in a known manner by allowing this melt to cool. After the block had cooled to an average temperature of about 600 ° C, it was crushed to grain sizes smaller than 150 mm and the carbide, which was still 500 ° C, was covered with so much lime with a grain size of 8 to 60 mm that the resulting mixture contained a total CaO content of 50% by weight.
• the mixture was then passed through to a particle size between 0 and 100 1 while passing 1500 m 3 / h of air with a moisture content of 10 g / m 3 (at 15 ° C) in a rotary mill with a throughput of 500 kg / h at 50 ° C Ground 1m.
• Calcium carbide is produced thermally from lime and coke in a known manner, the lime-coke mixture in the entire Möller being adjusted to a weight ratio of approximately 110:40, which corresponds to a carbide with a CaO content of approximately 45% by weight.
• CaO with a grain size of 3-8 mm is added to the tapping jet of this carbide in such an amount that an average content of approx. 80% by weight CaO results in the tapping crucible (about 1.2-1.3 t CaO per tonne of tapping jet).
• the block is pre-broken to a grain size of less than 150 mm and as much lime with a grain size of 8 to 60 mm is layered on the hot mixture that the average CaO content is 90% by weight.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Carbon And Carbon Compounds (AREA)
• Coating With Molten Metal (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Glass Compositions (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Citations (8)

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• 1979
  • 1979-12-29 DE DE19792952686 patent/DE2952686A1/de not_active Withdrawn
• 1980
  • 1980-12-12 ES ES497685A patent/ES8200146A1/es not_active Expired
  • 1980-12-15 DE DE8080107915T patent/DE3069043D1/de not_active Expired
  • 1980-12-15 EP EP80107915A patent/EP0031534B1/de not_active Expired
  • 1980-12-15 AT AT80107915T patent/ATE9101T1/de not_active IP Right Cessation
  • 1980-12-23 BR BR8008500A patent/BR8008500A/pt unknown
  • 1980-12-23 PL PL1980228751A patent/PL125648B1/pl unknown
  • 1980-12-23 IN IN1420/CAL/80A patent/IN153342B/en unknown
  • 1980-12-23 NO NO803924A patent/NO153500C/no unknown
  • 1980-12-23 DK DK550880A patent/DK151569C/da not_active IP Right Cessation
  • 1980-12-24 AU AU65854/80A patent/AU532989B2/en not_active Ceased
  • 1980-12-26 JP JP18417880A patent/JPS5698413A/ja active Granted
  • 1980-12-26 SU SU803221904A patent/SU1269739A3/ru active
  • 1980-12-29 ZA ZA00808064A patent/ZA808064B/xx unknown
  • 1980-12-29 DD DD80226699A patent/DD155527A5/de not_active IP Right Cessation
• 1981
  • 1981-01-02 US US06/222,086 patent/US4368071A/en not_active Expired - Fee Related
  • 1981-01-05 MX MX185478A patent/MX154954A/es unknown

Patent Citations (8)

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