Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
• • 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
  • C21C7/06—Deoxidising, e.g. killing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
  • Y02P10/143—Reduction of greenhouse gas [GHG] emissions of methane [CH4]

Definitions

• the present invention relates to a method of deoxidizing molten metal and more particularly to a method of deoxidizing molten metal while maintaining the carbon content of the metal at a level about equal to or lower than the level prior to deoxidizing.
• a lowering of the partial pressure of carbon monoxide changes equilibrium relationships and shifts the attainable end point carbon to lower levels without necessitating excessive oxidation of metallic components and, thereby, frees carbon to combine with oxygen within the melt.
• Reduction in the partial pressure can be accomplished by reducing the pressure in the vessel and/ or by introducing argon into the vessel.
• This third method does not measure up to theoretical expectations as the carbon-oxygen reaction fails to proceed to completion. From a thermodynamic point of view, the system acts as if it were under a higher pressure.
• the present invention provides a method which eti'ectively deoxidizes a melt while controlling the carbon content at a level about equal to or lower than that which was present prior to deoxidizing. It employs at least one hydrocarbon as a deoxidizer and at least one diluent gas.
• the diluent gas enables the processor to use small amounts of hydrocarbon deoxidizer, thereby precluding excessive injection of carbon into the melt, while maintaining a gaseous injection rate which is sufiicient to insure adequate mixing between the hydrocarbon deoxidizer and the melt.
• the hydrocarbon deoxidizer input rate can be lowered without reducing the rate of oxygen reaction with carbon, by introducing a diluent gas with the hydrocarbon deoxidizer.
• the present invention comprises the steps of introducing hydrocarbon deoxidizer and diluent gas into a vessel containing molten metal, determining the eiiect of the hydrocarbon deoxidizer and diluent gas upon the carbon content of the metal and controlling the proportion of hydrocarbon deoxidizer to diluent gas so that the average rate of carbon leaving the vessel is about equal to or greater than the average rate of carbon being introduced into the vessel.
• the invention embraces the use of one or more hydrocarbon deoxidizers chosen from a wide spectrum of gase- (ms and liquid hydrocarbons and hydrocarbon containing substances as well as the use of one or more diluent gases chosen from a wide spectrum of diluent gases.
• hydrocarbons and hydrocarbon containing substances are methane, ethane, propane, ethylene, water gas and natural gas.
• Illustrative diluent gases are argon, nitrogen, hydrogen and carbon monoxide.
• Liquid hydrocarbons and hydrocarbon containing substances require the additional step of atomizing the liquid into the diluent gas stream.
• the hydrocarbon deoxidizer and diluent gas can be blown into or blown onto the top of the melt.
• the efiiciency at which carbon and oxygen combined tells a processor what the proportion of hydrocarbon deoxidizer to diluent gas should be for subsequent heats, of similar chemistry, which are to be deoxidized under similar conditions, e.g., similar gaseous injection rates.
• a heat deoxidized with hydrocarbon deoxidizer and 20% diluent gas and having a 50% carbon-oxygen reaction etficiency indicates that subsequent heats should use 40% or less hydrocarbon deoxidizer and 60% or more diluent gas if the heats are of similar chemistry and are to be similarly deoxidized.
• An alternative process for detemining the effect of the hydrocarbon deoxidizer overcomes the shortcoming of the above described procedure. It involves calculating the rate at which carbon is introduced to the vessel and the rate at which it leaves the vessel.
• the carbon input rate can be calculated from the analysis and input rate of hydrocarbon deoxidizer and diluent gas.
• the carbon output rate can be calculated from the output rate and analysis of the gases exiting the vessel (a monitoring system can be used to analyze the exiting gases).
• the calculations enable a processor to control the carbon content of the melt by adjusting the rate at which carbon is introduced to the vessel.
• the hydrocarbon deoxidizer and the diluent gas are injected into the vessel at an average gaseous injection rate of at least 20 cu. ft. per hour.
• a preferred average gaseous injection rate is at least 30 cu. ft. per hour.
• Lower injection rates are, however, embraced within this invention. A precise value cannot be set for the minimum rate as it fluctuates with process variables, such as the depth of the molten metal.
• the invention can additionally encompass controlling of the final oxygen content. This entails knowledge of the oxygen content prior to or at some stage during deoxidation and calculating of the amount of oxygen leaving the system.
• Oxygen in the melt can be measured by an EMF cell or by chemical analysis.
• the amount of oxygen leaving the system can be calculated from an analysis of the gases exiting from the system and from the following equations:
• the carbon input and input rate can be obtained from the following equations:
• the carbon output and output rate can be obtained from the following equations:
• a method of deoxidizing molten steel and controlling its final oxygen content while maintaining a carbon level about equal to or lower than the carbon level which Was present prior to deoxidizing which comprises the steps of: analyzing molten steel to determine its oxygen content; introducing hydrocarbon deoxidizer and diluent gas at an average injection rate of at least 20 cu. ft.
• a method according to claim 1 wherein said introducing of hydrocarbon deoxidizer and diluent gas into 6 said vessel containing molten steel comprises the step of blowing hydrocarbon deoxidizer and diluent gas into said molten steel.
• a method according to claim 1 wherein said introducing of hydrocarbon deoxidizer and diluent gas into said vessel containing molten steel comprises the step of blowing hydrocarbon deoxidizer and diluent gas onto said molten steel.
• a method according to claim 1 wherein said determining of the efiect of said hydrocarbon deoxidizer and diluent gas upon the carbon content of said steel comprises the steps of: calculating the rate at which carbon is introduced into said vessel; and calculating the rate at which carbon leaves said vessel.
• a method according to claim 5 including the step of analyzing the gases exiting from said vessel.
• hydrocarbon deoxidizer is comprised of methane.
• said diluent gas is comprised of argon.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Manufacture And Refinement Of Metals (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22127689

Family Applications (2)

Family Applications After (1)

Country Status (10)

Cited By (10)

Families Citing this family (2)

Family Cites Families (3)

• 1970
  • 1970-09-25 US US00075738A patent/US3725041A/en not_active Expired - Lifetime
• 1971
  • 1971-09-15 AU AU33503/71A patent/AU461916B2/en not_active Expired
  • 1971-09-20 DE DE19712146923 patent/DE2146923A1/de active Pending
  • 1971-09-23 BR BR6270/71A patent/BR7106270D0/pt unknown
  • 1971-09-23 AT AT824171A patent/ATA824171A/de not_active Application Discontinuation
  • 1971-09-24 BE BE773040A patent/BE773040A/xx unknown
  • 1971-09-24 FR FR7134522A patent/FR2107994B1/fr not_active Expired
  • 1971-09-24 GB GB4462571A patent/GB1336357A/en not_active Expired
  • 1971-09-24 CA CA123,591A patent/CA947976A/en not_active Expired
  • 1971-09-25 ES ES395447A patent/ES395447A1/es not_active Expired
• 1972
  • 1972-11-24 US US00307661A patent/US3816104A/en not_active Expired - Lifetime

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