Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C35/00—Master alloys for iron or steel
  • C22C35/005—Master alloys for iron or steel based on iron, e.g. ferro-alloys

Definitions

• ABSTRACT composite provides, for example, a useful effective low silicon source of phosphorus and alloying -constituents for iron, steel and their alloys.
• This invention relates to composite compositions of ferro and non-ferro alloys useful in the metalurgical industries.
• a particularly preferred embodiment of this invention relates to composite compositions of ferrophosphorus suitable for use in the steel industry in the formation of phosphorus containing steels.
• Ferrophosphorus is a by-product of the well-known electric furnace processes for production of elemental phosphorus. Depending upon the compositions of ore fed to the furnace, the ferrophosphorus generally consists of to 30 percent phosphorus, from 55 to 80 percent iron and, in some instances, minor amounts of chromium, vanadium, titanium, manganese and nickel, etc. In addition, ferrophosphorus, particularly that derived as a by-product of the processing of phosphorus ores from the south-eastem part of the United States, often contains silicon in amounts up to 8.0 percent.
• ferrophosphorus to molten iron, steel, and alloys thereof is a convenient means of incorporating desired phosphorus contents into steel alloys.
• silicon or ferro-silicon
• ferrophosphorus used for such purpose has a silicon content less than 1 percent by weight, preferably less than 0.5 percent by weight or less. Accordingly, for such use, it has hitherto been necessary to select ferrophosphorus characterized by low silicon content as a result of the assay of the raw materials fed to the phosphorus furnace.
• ferrophosphorus having high silicon content can be processed to remove the silicon or convert the silicon to innocuous silica (which is insoluble in the molten metal).
• disiliconization treatments have hitherto proven undesirably expensive.
• the compositions of this invention comprise particulate metallic alloy materials less than 4 mesh 'U. S. standard sieve size having an elemental silicon (the term “elemental silicon” is used herein to exclude oxidized silicon--i.e., silica,but to include silicon alloyed or chemically associated with metallic components e.g., ferro-silicon) content of at least 1.0 percent by weight, admixed and in adherent contact with a quantity of calcium carbonate (which functions as an oxidizing agent) sufficient to convert a major proportion of the silicon to silica.
• elemental silicon the term "elemental silicon” is used herein to exclude oxidized silicon--i.e., silica,but to include silicon alloyed or chemically associated with metallic components e.g., ferro-silicon) content of at least 1.0 percent by weight, admixed and in adherent contact with a quantity of calcium carbonate (which functions as an oxidizing agent) sufficient to convert a major proportion of the silicon to silica.
• compositions of this invention provide alloying ingredients of "effective low silicon content (even though actual" silicon content is high, addition of the compositions to molten metal baths does not result in an equivalent increase in silicon content since a major proportion of the silicon is converted to silica).
• alloying ingredient is used to include ferroalloys such as ferrophosphorus, ferro-nickel, ferrochromium, ferro-vanadium, ferro-manganese, etc., and non-ferroalloys such as copper-nickel alloys which in the metallurgical industries are added to, for example, molten iron or steel to provide a desired phosphorus, nickel chromium, etc., content or used as raw materials for non-ferroalloys.
• the alloying ingredient must, of
• compositions of this invention are described herein with reference to ferrophosphorus as the alloying ingredient but it is to be understood that the teachings are, likewise, applicable when other alloying ingredients or mixtures thereof are utilized.
• a representative composition of this invention comprises ferrophosphorous containing silicon (probably present as ferro-silicon) and calcium carbonate.
• compositions of this invention are added to molten steel or steel alloy, it is unexpectedly found that the silicon content of the composition is substantially completely oxidized to silica. In order to obtain this surprising and advantageous result, it is essential that the composition possess certain critical characteristics as hereinafter discussed.
• the ferrophosphorus contained in the composition must be less than 4 mesh U. S. standard sieve size, preferably less than 30 mesh or even smaller. If larger particles of ferrophosphorus are utilized, the conversion of the silicon content of the ferrophosphorus to silica upon addition of the composition to molten steel or steel alloy is low even when excess oxidizer is employed.
• the ferrophosphorus utilized in the invention will contain at least 1 percent by weight silicon and generally substantially larger amounts, up to 8 percent, it being emphasized, however, that there is no theoretical upper limit on the silicon content.
• the oxidizing agent used in the compositions of this invention is calcium carbonate. This material in addition to functioning as an effective oxident, is highly desirable from the standpoint of availability and cost.
• the composition may advantageously contain Cal equivalent to 30 percent, SiO, equivalent to 25 percent or FeO equivalent to 60 percent of the weight of CaCO
• Higher iron oxides Pep, or Fe O can advantageously serve as a source of flux and as a supplementary oxidizing agent.
• a particularly preferred combination for admixture with the ferrophosphorus consists of from 80 to 20 percent CaCO and 20- 80 percent iron oxides.
• the amount of calcium carbonate which must be composited with the ferrophosphorus to convert the desired amount of silicon to silica is readily determined by routine testing.
• the ferrophosphorus is finely divided, the actual oxidizer requirements approximate stoichiometric requirements.
• the ferrophosphorus is coarser, excess oxider is required.
• the use of finely divided (less than 30 mesh, preferably less than 100 mesh U. S. standard sieve size) ferrophosphorus to avoid necessity of wasteful oxidizer excesses is preferred.
• ferrophosphorus, calcium carbonate and flux be thoroughly admixed and composited so that upon addition to a molten metal bath, the calcium carbonate will remain in integral contact with the ferrophosphorus for a length of time sufficient to effect oxidization of the silicon contained therein.
• Integral compositing can be conveniently obtained by admixing the particulate ferrophosphorus with calcium carbonate and flux and dampening the mixture so that the oxidizing agent adheres to the ferrophosphorus particles. The composite is then dried, leaving the oxidizing agent in adherent contact with the ferrophosphorus particles. In drying, it is desirable to use conditions adequate to completely remove water in order that undue rapid disintegration of the composite does not take place upon its addition to molten metal.
• integral compositing can be effected by pelletizing or briqueting mixtures of ferrophosphorus, flux, and oxidizing agent in accordance with conventional procedures.
• a binder can be incorporated in the mixture to improve pellet or briquette strength. Conversion of the composition of this invention into pellets, briquets, or other shaped forms is particularly desirable for convenience in handling.
• composition of this invention and their use are further illustrated by the following examples wherein all parts and percentages are by weight.
• a shaped composite composition is prepared as follows:
• the slag formed was observed to be much less viscous than in Example I demonstrating the desirability of using a fluxing agent.
• a composite composition comprising particulate ferrophosphorus less than 4 mesh U.S. standard sieve size having an elemental silicon content of at least 1.0 percent by weight, said ferrophosphorus being admixed and in adherent contact with sufficient calcium carbonate to convert at least a major proportion of the said silicon to silica.
• a composite composition having a shaped, integral form and comprising particulate ferrophosphorus less than 4 mesh U.S. standard sieve size having an elemental silicon content of at least 1.0 percent by weight substantially uniformly admixed with sufficient calcium carbonate to convert at least a major proportion of said silicon to silica.
• composition of claim 3 additionally containing a fluxing agent.
• said fluxing agent is an iron oxide selected from the group consisting of Fe,O Fe O and mixtures thereof, said fluxing agent being present in an amount equal to from 20-80 percent of the weight of said calcium carbonate.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Treatment Of Steel In Its Molten State (AREA)

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Citations (10)

Family Cites Families (2)

• 1970
  • 1970-06-29 US US00064836A patent/US3718459A/en not_active Expired - Lifetime
• 1971
  • 1971-06-28 SE SE7108335A patent/SE392732B/xx unknown
  • 1971-06-28 BE BE769138A patent/BE769138A/xx not_active IP Right Cessation
  • 1971-06-28 DE DE19712132023 patent/DE2132023A1/de not_active Withdrawn
  • 1971-06-28 GB GB3018471A patent/GB1331384A/en not_active Expired
  • 1971-06-28 CA CA116,867A patent/CA949329A/en not_active Expired
  • 1971-06-28 FR FR7123512A patent/FR2099998A5/fr not_active Expired

Patent Citations (10)

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