Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
  • C22C27/04—Alloys based on tungsten or molybdenum

Definitions

• a porous, solid-shaped additive for steel baths which comprises a composition having, by weight, a molybdenum content in the range 40 to 95%, an iron content in the range to 50% and a carbon content in the range 0.2 to 5%, the density of the composition being in the range 2.5to 5.0 grams per cubic centimeter.
• the preferred molybdenum content is 60 to 70%, the preferred iron content is to 30% and the preferred carbon content is 0.2 to 1.5%.
• Up to 10% by weight of impurities can generally be tolerated in the composition. The impurities will tend toaccumulate in the slag in the steel bath and will be removed along with it.
• a density within the claimed range is found important in order to ensure that the added composition rests at the interface between the molten steel and the molten slag layer. Upon contact with the surface of the molten steel the composition begins to melt and to dissolve into the melt. Preferably the density is within the range 3 to 4 grams'per cubic centimeter.
• composition In order to fall within the desired density range the composition must be held together with a suitable binder.
• suitable binder examples include molasses, starch,-dextrine and tar.
• the invention also provides a method for making a composition having, by weight, a molybdenum content in the range 40 to 95%, an iron content in the range 10 to 50%, a carbon content in the range 0.2 to 5%, a binder and a density in the range 2.5 to 5 grams per cubic centimeter. which comprises adding together a molybdenum-containing material, an iron-containing material, carbon and a binder and heating the mixture so formed at a temperature in the range 850 to 1500C for a period of at least one hour.
• the molybdenumcontaining material is preferably molybdenum trioxide. This is the product of roasting molybdenum ore. Pure molybdenum trioxide can be employed if desired and a partly-reduced molybdenum trioxide is also suitable.
• the iron is preferably introduced in the form of iron oxide, conveniently in the form of iron scale. (for example millscale.) but other forms are possible. for ex ample ground iron.
• the iron-containing material is preferably of a particle size below 30 mesh 885.
• the proportion of binder required depends on the particular binder employed but is typically within the range 2 to 5% of the weight of the composition.
• the binder can if desired be employed in admixture with water.
• I 1 i The preferred temperature range for forming the composition is 1 150 and 1 350C. Working within this range is found to give a more reduced product, improved strength and less risk of fusion. It also gives a density greater than can be achieved below 1 150C.
• the materials to form the composition are introduced into a cold furnace which is then allowed to warm up to the desired temperature level.
• the gradual raising of the temperature of the introduced mixture is conveniently achieved by passing the mixture through a tunnel in which the temperature gradually builds up from ambient to the desired working temperature.
• a particular advantage of the present invention is that the composition lends itself to being formed into a'variety of convenient types. Thus it can be formed into nodules, briquettes and can if desired be extruded into rods. Whichever form is chosen, the discrete lumps of the composition to be added to the steel bath are preferably of a weight in the range 50 to grams.
• the products of the invention have the advantage of.
• the process of the invention is advantageous in being readily employable in a continuous manner. Moreover, since the product can be obtained in the form of small nodules of briquettes of predetermined weight, the addition of carefully controlled quantities of molybdenum to the steel is simplified.
• EXAMPLE 1 A mixture of 260 grams roasted molybdenite, 86 grams millscale (FeO) and 30 grams carbon was placed in a glass bottle of l kilogram capacity which was placed on revolving rollers for one hour to mix the contents. 15 grams molasses in 10 ml water was then added with stirring.
• the wet mixture was formed into briquettes using a pressure of tons per squareinch.
• the briquettes were packed in carbon in a carbon crucible and introduced into an induction furnace.
• the purpose of the enveloping layer of carbon was to protect the briquettes from the oxidising atmosphere in the furnace.
• the temperature in the furnace was increased over a period of l /2 hours up to a temperature of 1320C. The temperature was maintained at this level for 2 hours and the crucible was then allowed to cool to room temperature.
• the briquettes so formed each weighed about 67 grams, had a density of 2.8 grams per cubic centimeter and the following analysis, by weight:
• Example 2 The procedure of Example I was followed. using a mixture of 290 grams roasted molybdenum, 75 grams millscale, 35 grams of charcoal and 15 grams of molasses. The temperature in the furnace was raised from ambient to l,33()C.
• the briquettes so formed each weighed about 68 grams, had a density of 3.8 grams per cubic centimeter and, the following analysis, by weight:
• An additive for molten steel baths which consists lybdenum content is 60 to the iron content is 20 to 30% and the carbon content is 0.2 to 1.5%.
• a method for making a porous, solid-shaped composition which permits ready dissolution at the interface between the molten steel and molten slag layer in a molten steel bath consisting essentially of and having by weight, a molybdenum content in the range 40 to an iron content in the range 10 to 50%, a carbon content in the range 0.2 to 5%, and a binder being a member of the group consisting of molasses, starch, dextrine and tar and a density in the range 2.5 to 5 grams per cubic centimeter which consists essentially of adding together a molybdenum-containing material, an iron-containing material, carbon and said binder and heating the mixture so formed at a temperature in the range 850 to 1500C. for a period of at least one hour. 1
• An additive as claimed in claim 1 whcrein'the solidshapeis in the form of a briquette having a density of 2.8 and an analysis by weight of 64.6 molybdenum, 25.371 iron, 0.9% carbon and a slag content of 8.0%.
• An additive as claimed in claim ,1 wherein the solid shape is in the form of a briquette having a density of 3.8 and an analysis by weight of 69.4% molybdenum, 19.8% iron, 1.2% carbon and a slag content of 8.8%.

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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)
• Manufacture And Refinement Of Metals (AREA)
• Carbon Steel Or Casting Steel Manufacturing (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10277677

Family Applications (1)

Country Status (13)

Cited By (3)

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Citations (4)

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• 1973
  • 1973-06-15 GB GB2856873A patent/GB1472255A/en not_active Expired
• 1974
  • 1974-06-12 DE DE19742428459 patent/DE2428459A1/de active Pending
  • 1974-06-12 PL PL1974171845A patent/PL90350B1/pl unknown
  • 1974-06-13 AU AU70078/74A patent/AU7007874A/en not_active Expired
  • 1974-06-13 LU LU70316A patent/LU70316A1/xx unknown
  • 1974-06-14 JP JP49068024A patent/JPS5033110A/ja active Pending
  • 1974-06-14 BE BE145450A patent/BE816365A/xx unknown
  • 1974-06-14 FR FR7420831A patent/FR2233412B1/fr not_active Expired
  • 1974-06-14 ES ES427260A patent/ES427260A1/es not_active Expired
  • 1974-06-14 AT AT491774A patent/AT339352B/de not_active IP Right Cessation
  • 1974-06-14 IT IT51534/74A patent/IT1013476B/it active
  • 1974-06-17 US US480155A patent/US3907554A/en not_active Expired - Lifetime
  • 1974-06-17 SE SE7407988A patent/SE7407988L/xx not_active Application Discontinuation

Patent Citations (4)

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