FERROSILICON VANADIUM AND/OR NIOBIUM ALLOY, PRODUCTION OF A FERROSILICON VANADIUM AND/OR NIOBIUM ALLOY, AND THE USE THEREOF

Abstract

A ferrosilicon vanadium and/or niobium (FeSi V and/or Nb) alloy having 15-80 wt % Si; 0.5-40 wt % V and/or Nb; up to 10 wt & Mo; up to 5 wt % Cr; up to 3 wt % Cu; up to 3 wt % Ni; up to 20 wt % Mg; 0.01 to 7 wt % Al; up to 13 wt % Ba; 0.01 to 7 wt % Ca; up to 13 wt % Mn; up to 8 wt & Zr; up to 12 wt & La and/or Ce and/or misch metal; up to 5 wt % Sr; up to 3 wt % Bi; up to 3 wt & Sb; up to 1.5 wt % Ti; balance Fe and incidental impurities; a method for the production of a FeSi V and/or Nb alloy and the use thereof in cast iron.

Claims

1.-26. (canceled)

27. A ferrosilicon vanadium and/or niobium (FeSi V and/or Nb) alloy, comprising 15-80 wt % Si; 5-35 wt % V and/or Nb; up to 10 wt % Mo; up to 5 wt % Cr; up to 3 wt % Cu; up to 3 wt % Ni; up to 20 wt % Mg; 0.01-7 wt % Al; up to 13 wt % Ba; 0.01-7 wt % Ca; up to 13 wt % Mn; up to 8 wt % Zr; up to 12 wt % La and/or Ce and/or misch metal; up to 5 wt % Sr; up to 3 wt % Bi; up to 3 wt & Sb; up to 1.5 wt % Ti; balance Fe and incidental impurities.

28. The FeSi V and/or Nb alloy according to claim 27, wherein the FeSi V and/or Nb alloy comprises 15-29 wt & Si; 5-35 wt % V and/or Nb; up to 10 wt % Mo; up to 5 wt % Cr; up to 3 wt Cu; up to 3 wt % Ni; up to 20 wt % Mg; 0.01 to 7 wt % Al; up to 13 wt % Ba; 0.01 to 7 wt % Ca; up to 13 wt % Mn; up to 8 wt % Zr; up to 12 wt % La and/or Ce and/or misch metal; up to 5 wt % Sr; up to 3 wt % Bi; up to 3 wt & Sb; up to 1.5 wt % Ti; balance Fe and incidental impurities.

29. The FeSi V and/or Nb alloy according to claim 27, wherein the FeSi V and/or Nb alloy comprises from 30-50 wt % Si; from 16-35 wt % V and/or Nb; up to 10 wt & Mo; up to 5 wt % Cr; up to 3 wt % Cu; up to 3 wt % Ni; up to 20 wt % Mg; 0.01 to 7 wt % Al; up to 13 wt % Ba; 0.01 to 7 wt % Ca; up to 13 wt & Mn; up to 8 wt % Zr; up to 12 wt % La and/or Ce and/or misch metal; up to 5 wt % Sr; up to 3 wt % Bi; up to 3 wt % Sb; up to 1.5 wt % Ti; balance Fe and incidental impurities.

30. The FeSi V and/or Nb alloy according to claim 27, wherein the FeSi V and/or Nb alloy comprises from 51-80 wt % Si; 5-35 wt % V and/or Nb; up to 10 wt & Mo; up to 5 wt % Cr; up to 3 wt % Cu; up to 3 wt & Ni; up to 20 wt % Mg; 0.01 to 7 wt % Al; up to 13 wt % Ba; 0.01 to 7 wt % Ca; up to 13 wt % Mn; up to 8 wt % Zr; up to 12 wt % La and/or Ce and/or misch metal; up to 5 wt % Sr; up to 3 wt % Bi; up to 3 wt % Sb; up to 1.5 wt % Ti; balance Fe and incidental impurities.

31. The FeSi V and/or Nb alloy according to claim 27, comprising up to 15 wt % Mg.

32. The FeSi V and/or Nb alloy according to claim 27, comprising up to 5 wt % Mo.

33. The FeSi V and/or Nb alloy according to claim 27, wherein the FeSi V and/or Nb alloy has a melting temperature range from 1060 to 1640? C.

34. The FeSi V and/or Nb alloy according to claim 27, wherein the FeSi V and/or Nb alloy is in the form of particles or lumps having a sizing of 0.06 mm to 50 mm.

35. The FeSi V and/or Nb alloy according to claim 34, wherein the FeSi V and/or Nb particles or lumps are coated or mixed with bismuth oxide, and/or bismuth sulfide, and/or antimony sulfide, and/or antimony oxide, and/or other metal oxide like iron oxide, and/or another metal sulfide like iron sulphide.

36. The FeSi V and/or Nb alloy according to claim 27, wherein the FeSi V and/or Nb alloy is an additive for use in production of cast iron.

37. A method for production of a ferrosilicon vanadium and/or niobium (FeSi V and/or Nb) alloy according to claim 27, the method comprises: providing a ferrosilicon alloy in molten state; adding vanadium oxide containing raw material and/or niobium oxide containing raw material to the molten ferrosilicon alloy, where the vanadium oxide containing raw material and/or niobium oxide containing raw material is added in an amount (by weight) providing essentially the target amount of elemental vanadium and/or niobium (by weight) in the FeSi V and/or Nb alloy; mixing and reacting the molten ferrosilicon alloy and vanadium oxide from the vanadium oxide containing raw material and/or niobium oxide from the niobium oxide containing raw material, thereby forming a melt of FeSi V and/or Nb alloy and slag; separating the slag from the said melt; and solidifying or casting the molten FeSi V and/or Nb alloy.

38. The method according to claim 37, where the molten ferrosilicon alloy is provided directly from a reduction furnace, wherein ferrosilicon is as-produced from raw materials according to conventional methods.

39. The method according to claim 37, where the molten ferrosilicon alloy re-melting a charge of ferrosilicon alloy.

40. The method according to claim 37, wherein the vanadium oxide containing raw material is one or more vanadium oxide phases selected from vanadium (II) oxide, vanadium (III) oxide, vanadium (IV) oxide, vanadium (V) oxide, and/or other non-principal oxides of vanadium and/or niobium oxide raw material is one or more niobium oxide phases selected from niobium (II) oxide, niobium (III) oxide, niobium (IV) oxide, niobium (V) oxide, and/or other non-principal oxides of niobium.

41. The method according to claim 40, where the vanadium oxide phase is vanadium (V) oxide, V.sub.2O.sub.5 and/or vanadium (III) oxide, V.sub.2O.sub.3 and/or niobium oxide phase is niobium (V) oxide, Nb.sub.2O.sub.5 and/or niobium (III) oxide, Nb.sub.2O.sub.3.

42. The method according to claim 40, wherein the vanadium oxide containing raw material further comprises industrial waste material or ore comprising vanadium oxide, and/or the niobium oxide containing raw material further comprises industrial waste material or ore comprising niobium oxide.

43. The method according to claim 37, where a slag modifying compound is added to the molten ferrosilicon alloy in an amount of 0.5-30 wt %, based on the total amount of ferrosilicon alloy and vanadium oxide and/or niobium oxide.

44. The method according to claim 43, wherein the slag modifying compound is at least one of Cao and MgO.

45. The method according to claim 37, wherein the molten starting ferrosilicon alloy comprises: 40-90 wt % Si; up to 0.5 wt & C; 0.01-7 wt % Al; up to 6 wt % Ca; up to 1.5 wt % Ti; up to 15 wt % Mn; up to 10 wt % Cr; up to 10 wt % Zr; up to 15 wt % Ba; up to 0.3 wt % P; up to 0.5 wt % S; the balance being Fe and incidental impurities.

46. The method according to claim 37, further comprising adding aluminium to the ferrosilicon melt, prior to, simultaneously, or after the addition of t the vanadium oxide containing raw material and/or the niobium oxide containing raw material, in an amount of up to 10 wt %, based on the total amount of ferrosilicon and vanadium oxide and/or niobium oxide.

47. The method according to claim 37, wherein the molten ferrosilicon alloy and the vanadium oxide containing raw material and/or the niobium oxide containing raw material, and any added aluminium and/or slag modifying compound, are mixed by mechanical stirring or gas stirring.

48. The method according to claim 37, wherein the slag is separated before or during casting of the molten ferrosilicon vanadium and/or niobium alloy.

49. The method according to claim 37, wherein the solidified casted FeSi V and/or Nb is formed into blocks or crushed and optionally graded in size fractions or agglomerated.

50. An additive comprising theFeSi V and/or Nb alloy according to claim 27 for use in the manufacture of vanadium and/or niobium containing cast iron.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0060] FIG. 1 is a diagram showing a comparison of dissolution time of different FeSiV alloys according to an embodiment of the present invention in a cast iron melt at 1400? C.

[0061] FIG. 2 is a diagram showing a comparison of dissolution time of different FeSiV alloys according to an embodiment of the present invention, and a standard FeV80 alloy in a cast iron melt at 1500? C.

[0062] FIG. 3 is a diagram showing a comparison of dissolution time of different FeSiNb alloys according to an embodiment of the present invention, and a standard FeNb65 alloy in a cast iron melt at 1500? C.

[0063] FIG. 4 is a diagram showing a comparison of dissolution time of FeSiNbV and FeSiNbVMo alloys according to an embodiment of the present invention, and a standard FeNb65 and a standard FeV80 alloy in a cast iron melt at 1500? C.

DETAILED DESCRIPTION

[0064] The ferrosilicon vanadium and/or niobium alloy according to the first aspect is especially suitable for use as an additive in cast iron production, for the production of vanadium and/or niobium containing cast iron. The first aspect of this invention relates to a FeSi V and/or Nb alloy comprising 15-80 wt % Silicon (Si); 0.5-40 wt % Vanadium (V) and/or Niobium (Nb); up to 10 wt % Molybdenum (Mo); up to 5 wt % Chromium (Cr); up to 3 wt % Cu; up to 3 wt % Ni; up to 20 wt % Magnesium (Mg); 0.01 to 7 wt % Aluminium (Al); up to 13 wt % Barium (Ba); 0.01 to 7 wt % Calcium (Ca); up to 13 wt % Manganese (Mn); up to 8 wt % Zirconium (Zr); up to 12 wt % Lanthanum (La) and/or Cerium (Ce) and/or misch metal; up to 5 wt % Strontium (Sr); up to 3 wt % Bismuth (Bi); up to 3 wt % Antimony (Sb); up to 1.5 wt % Titanium (Ti); balance iron (Fe) and incidental impurities.

[0065] The present FeSi V and/or Nb alloy is especially suitable as an additive in cast iron manufacturing.

[0066] Further, the FeSi V and/or Nb alloy according to the present invention has a lower melting temperature and a different dissolution route in molten cast iron compared with the conventional FeV80 or FeNb65 alloy. The potential lower melting temperature and different dissolution route lead to significantly higher dissolution rates in molten iron compared to FeV80 or FeNb65. The lower melting temperature and higher dissolution rate lead to reduced energy consumption when added to molten cast iron and result in better distribution of vanadium and/or niobium in the melt, which the lower densities of the alloys from the present invention might also improve. Furthermore, a higher dissolution rate means that the ferrosilicon vanadium and/or niobium additive alloy can be added later in the cast iron manufacturing process, which may lead a better flexibility of the process in the foundry.

[0067] Furthermore, the densities of the FeSi V and/or Nb alloy according to the present invention are lower than the densities of FeV80 and FeNb65. Added in the furnace or at the bottom of a ladle, their dissolution will not lead to segregation of V and Nb at the bottom. For example, added at the bottom of a ladle, the alloy pieces according to the present invention, which have a lower density than iron and will start to move upwards while dissolving. On the contrary, FeNb65 pieces for example would stay at the bottom of the ladle and dissolve there leading to a higher niobium concentration at the bottom.

[0068] Silicon is a common additive in the manufacture of cast iron. Silicon is an alloying element in cast iron ranging from 1 to 4.3 wt %. Silicon has an essential role in the production of cast iron (grey, compacted and ductile) and helps the nucleation of graphite rather than cementite. Silicon is also known to increase strength, wear resistance, elasticity and resistance to oxidation. The amount of Si in the present FeSi V and/or Nb alloy is between 15 and 80 wt %. In an embodiment, the amount of Si is at least 15 wt %; or at least 30 wt %; or at least 45 wt %; such as at least 51 wt % or at least 55 wt %. In an embodiment, the amount of Si is up to 75 wt %; such as up to 65 wt %; or up to 50 wt %; or up to 29 wt %.

[0069] The present FeSi V and/or Nb alloy comprises between 0.5 and 40 wt % V and/or Nb. This means that if only V is present it may be present in the range 0.5-40 wt %. If only Nb is present, it may be present in the range 0.5-40 wt %. If both V and Nb are present, the total amount of V and Nb in the alloy is in the range 0.5-40 wt %. If both V and Nb are present, they may be present in any ratio of V to Nb within the given range. In an embodiment, the amount of V and/or Nb is between 5-35 wt %. Vanadium and niobium form stable nitrides and carbides, resulting in a significant increase in the strength of cast iron. The strengthening of cast iron may also happen by pearlite promotion, refined pearlite lamella spacing or reined cell structures from the micro-alloying elements (V, Nb). Age hardening effect during annealing heat treatment (typically 1000-1100? C.), from primary carbide dissolution and re-precipitation of nano carbides upon cooling may also be obtained. Improved impact toughness, especially in un-notched samples, improved fatigue life properties in cyclic load applications of castings, improved wear resistance properties from carbide precipitates, especially in grey irons are other improvements that have been related to the use of V and Nb. Austempered ductile iron (ADI) is a heat treated material with excellent strength, wear and fatigue properties. In the production of ADI, alloying elements such as V and Nb are frequently applied to improve hardenability.

[0070] The V and/or Nb to Si range in the FeSiV alloy may depend on the amount of Si in the starting ferrosilicon alloy from which the FeSi V and/or Nb alloy is produced, e.g. a FeSi50 or FeSi65 alloy might provide a higher V and/or Nb to Si range compared to when starting from e.g. a FeSi75 alloy.

[0071] In some embodiments, the FeSi V and/or Nb alloy may comprise from 15 to 29 wt % Si, and from 0.5 to 40 wt % V and/or Nb, such as from 5-35 wt % V and/or Nb, or 9-30 wt % V and/or Nb, with the other elements as defined above according to the first aspect (up to 10 wt % Molybdenum (Mo); up to 5 wt % Chromium (Cr); up to 3 wt % Copper (Cu); up to 3 wt % Nickel (Ni); up to 20 wt % Magnesium (Mg); 0.01 to 7 wt % Aluminium (Al); up to 13 wt % Barium (Ba); 0.01 to 7 wt % Calcium (Ca); up to 13 wt % Manganese (Mn); up to 8 wt % Zirconium (Zr); up to 12 wt % Lanthanum (La) and/or Cerium (Ce), and/or misch metal; up to 5 wt % Strontium (Sr); up to 3 wt % Bismuth (Bi); up to 3 wt % Antimony (Sb); up to 1.5 wt % Titanium (Ti); balance Fe and incidental impurities).

[0072] In some embodiments, the FeSi V and/or Nb alloy may comprise from 30 to 50 wt % Si and 16-40, such as 16-35 wt % V and/or Nb, or 16-30 V and/or Nb, with the other elements as defined above according to the first aspect (up to 10 wt % Molybdenum (Mo); up to 5 wt % Chromium (Cr); up to 3% Copper (Cu); up to 3% Nickel (Ni); up to 20 wt % Magnesium (Mg); 0.01 to 7 wt % Aluminium (Al); up to 13 wt % Barium (Ba); 0.01 to 7 wt % Calcium (Ca); up to 13 wt % Manganese (Mn); up to 8 wt % Zirconium (Zr); up to 12 wt % Lanthanum (La) and/or Cerium (Ce) and/or misch metal; up to 5 wt % Strontium (Sr); up to 3 wt % Bismuth (Bi); up to 3 wt % Antimony (Sb); up to 1.5 wt % Titanium (Ti); balance Fe and incidental impurities)

[0073] In other embodiments, the FeSi V and/or Nb alloy may comprise from 51 to 80 wt % Si, such as 55-75 wt % Si, or 58-72 wt % Si, or 60-72 wt % Si, and from 0.5 to 40 wt % V and/or Nb, such as from 5-35 wt % V and/or Nb, or 9-30 wt % V and/or Nb, with the other elements as defined above according to the first aspect (up to 10 wt % Molybdenum (Mo); up to 5 wt % Chromium (Cr); up to 3 wt % Copper (Cu); up to 3 wt % Nickel (Ni); up to 20 wt % Magnesium (Mg); 0.01 to 7 wt % Aluminium (Al); up to 13 wt % Barium (Ba); 0.01 to 7 wt % Calcium (Ca); up to 13 wt % Manganese (Mn); up to 8 wt % Zirconium (Zr); up to 12 wt % Lanthanum (La) and/or Cerium (Ce), and/or misch metal; up to 5 wt % Strontium (Sr); up to 3 wt % Bismuth (Bi); up to 3 wt % Antimony (Sb); up to 1.5 wt % Titanium (Ti); balance Fe and incidental impurities).

[0074] It should be understood that several V and/or Nb to Si ranges can be realized within the above defined alloy compositions.

[0075] The FeSi V and/or Nb alloy comprises up to 10 wt % Mo. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 5 wt % Mo, or up to 3 wt % Mo, or up to 1 wt % Mo. Molybdenum is also an alloying element often used in some grades of cast iron like austempered ductile iron (ADI). Molybdenum is providing hardenability and stabilizing structures for high temperature applications. In grey irons, molybdenum has been reported to increase tensile strength (by 20% at 0.5 wt % Mo in cast iron) and hardness (by 10% at 0.5 wt % in cast iron). Molybdenum refines pearlite.

[0076] The FeSi V and/or Nb alloy comprises up to 5 wt % Cr. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 2 wt % Cr. Cr is an alloying element and has been reported to increase tensile strength and hardness. It is used together with vanadium and/or niobium in some cast iron grades.

[0077] The FeSi V and/or Nb alloy comprises up to 3 wt % Cu. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 1 wt % Cu, or up to 0.5 wt % Cu. Copper can be used to counteract the strong eutectic iron carbide formation promoted by vanadium and/or niobium.

[0078] The FeSi V and/or Nb alloy comprises up to 3 wt % Ni. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 1 wt % Ni, or up to 0.5 wt % Ni. Nickel can be used to counteract the strong eutectic iron carbide formation promoted by vanadium and/or niobium.

[0079] The following disclosure relating to the amounts of further elements Mg, Al, Ba, Ca, Mn, Zr, La, Ce, Sr, Bi, Sb, Ti, balance Fe and incidental impurities applies to each of the above mentioned embodiments, unless otherwise stated. These elements are commonly used in treatment alloys for the production of cast iron.

[0080] The FeSi V and/or Nb alloy comprises up to 20 wt % Mg. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 15 wt % Mg, or up to 10 wt % Mg. In some embodiments, with low Si level, such as Si in the range 15-35 wt %, the alloy may be without any Mg present. Magnesium is mostly used in nodularising treatments to desulphurise and deoxidise the melt which will result in a change of the graphite form from flake to nodules. Magnesium can also be used in lower concentrations in inoculants. The solubility of magnesium in iron is limited, thus there is a lower limit of silicon content necessary in a ferrosilicon alloy to allow for magnesium alloying.

[0081] The FeSi V and/or Nb alloy comprises 0.01 to 7 wt % Al. According to some embodiments, the FeSi V and/or Nb alloy comprises from 0.01 to 5 wt % Al or from 0.05 to 5 wt % Al.

[0082] The FeSi V and/or Nb alloy comprises up to 13 wt % Ba. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 11 wt % Ba, or up to 8 wt %, such as up to 6 wt % Ba. In some embodiments, the FeSi V and/or Nb may comprise 1-5 wt % Ba and 11-40 wt % V and/or Nb.

[0083] The FeSi V and/or Nb alloy comprises 0.01 to 7 wt % Ca. According to some embodiments, the FeSi V and/or Nb alloy comprises from 0.01 to 5 wt % Ca or from 0.05 to 5 wt % Ca.

[0084] The FeSi V and/or Nb alloy comprises up to 13 wt % Mn. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 8 wt % Mn, or up to 5 wt % Mn. In some embodiments, the FeSi V and/or Nb may comprise up to 13 wt % Mn, up to 8 wt % or up to 5 wt % Mn and 10-40 wt % V and/or Nb.

[0085] The FeSi V and/or Nb alloy comprises up to 8 wt % Zr. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 5 wt % Zr.

[0086] The FeSi V and/or Nb alloy comprises up to 12 wt % La and/or Ce, and/or misch metal. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 7 wt % La and/or Ce, and/or misch metal. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 4 wt % La and/or Ce, and/or misch metal. Mischmetal is an alloy of rare-earth elements, typically comprising approx. 50% Ce and 25% La, with small amounts of Nd and Pr. Lately heavier rare earth metals are often removed from the mischmetal, and the alloy composition of mischmetal may be about 65% Ce and about 35% La, and traces of heavier RE metals, such as Nd and Pr.

[0087] The FeSi V and/or Nb alloy comprises up to 5 wt % Sr. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 3 wt % Sr.

[0088] The FeSi V and/or Nb alloy comprises up to 3 wt % Bi. According to some embodiments, the FeSi V and/or Nb alloy comprises up to 1.8 wt % Bi.

[0089] The FeSi V and/or Nb alloy comprises up to 3 wt % Sb. According to some embodiments, the FeSi V and/or Nb comprises up to 1.5 wt % Sb.

[0090] The FeSi V and/or Nb alloy comprises up to 1.5 wt % Ti. According to some embodiments, the FeSi V and/or Nb comprises up to 0.5 wt % Ti. Titanium is normally present in low amounts in the starting ferrosilicon alloy. Titanium may also come from the vanadium oxide raw material and/or niobium oxide raw material added during the production of the FeSi V and/or Nb alloy. Titanium is harmful in some cast iron grades as it can form hard carbides and nitrides that lead to brittleness and reduced fatigue stress. It also reduces the tolerance level for other subversive elements. Therefore, the content of Ti in FeSi V and/or Nb alloy is preferably low, such as up to 0.1 wt %, or up to 0.05 wt %.

[0091] The FeSi V and/or Nb alloy may comprise minor amounts of C, P and S. The said elements can be normally present in small amounts in as-produced ferrosilicon or be added via the vanadium oxide raw material and/or the niobium oxide raw material and/or slag modifying compound added during the production of the FeSi V and/or Nb alloy. The said elements in the indicated amounts will typically not be critical for cast iron production. Of the elements above it will be P which can be most problematic as it leads to formation of low melting steadite found in last to freeze areas. Steadite undergoes substantial contraction during solidification leading to shrinkage porosities and reduced strength.

[0092] The FeSi V and/or Nb alloy, according to any of the above said embodiments, is advantageously in the form of lumps. In the present context, the term lumps denotes particles or pieces of the FeSi V and/or Nb alloy, e.g. of crushed FeSi V and/or Nb metal. The FeSi V and/or Nb alloy lumps may be produced in different size grades. According to some embodiments, the FeSi V and/or Nb alloy is in the form of particles or lumps having a sizing of between 0.06-50 mm. Common sizings used within cast iron making are from about 0.2 mm to about 50 mm. The term sizing refers to the size of the holes in a sieve that a lump fits through. Thus, according to some embodiments, the FeSi V and/or Nb alloy is in the form of particles or lumps having a sizing of between 0.2-50 mm. It should be understood that the average size may vary within this given range and smaller and larger sizes of the FeSi V and/or Nb lumps are possible depending on applications. According to some embodiments, the FeSi V and/or Nb alloy is in the form of an insert, such as a cast block or an agglomeration of powder material.

[0093] According to some embodiments, the FeSi V and/or Nb particles can be coated or mixed with bismuth oxide, and/or bismuth sulfide, and/or antimony sulfide, and/or antimony oxide, and/or other metal oxide like iron oxide, and/or another metal sulfide like iron sulphide.

[0094] The FeSi V and/or Nb alloy, according to any of the above said embodiments, has a melting temperature range from about 1060 to about 1640? C., or to about 1610? C. The relatively low melting temperature and different dissolution route of the present FeSi V and/or Nb alloy in an iron melt has the effect that the FeSi V and/or Nb added to an iron melt dissolves relatively rapid. Tests performed by the inventors have shown that lumps of the present FeSi V (30 wt % V) having a size about 18 mm would be completely assimilated by the melt after 50 s at 1400?C while a lump of FeV80 of the same size would still have not been assimilated at all after 3 min. The assimilation time for a 20 mm large lump would be twice as much for FeNb65 compared to FeSiNb20 at 1500? C.

[0095] FIG. 1 is a diagram showing dissolution time of different FeSi V alloys according to the present invention in an iron melt at a temperature of about 1400? C. The diagram shows dissolution time vs. different sizing of the FeSi V alloys. At this temperature, lumps of FeV80 of sizes between 7 and 18 mm were monitored for approximately 3 minutes but did not dissolve at all and are thus not represented in the plot.

[0096] FIG. 2 is a diagram showing dissolution time of different FeSi V alloys according to the present invention, compared to a standard commercial FeV80 alloy in an iron melt at a temperature of about 1500? C. The diagram shows dissolution time vs. different sizing of the FeSi V alloys and FeV80 lumps. The dissolution time of FeV80 alloy becomes significantly longer as the size of the lumps added to the iron melt increases, compared to the FeSi V alloys. Table 3 shows a significant higher yield of V for a FeSi V alloy compared to FeV80, both alloys having the same sizing when added to the melt.

[0097] FIG. 3 is a diagram showing dissolution time of different FeSi Nb alloys according to the present invention, compared to a standard commercial FeNb65 alloy in an iron melt at a temperature of about 1500? C. The diagram shows dissolution time vs. different sizing of the FeSi Nb alloys and FeNb65 lumps. The dissolution time of FeV80 alloy becomes significantly longer as the size of the lumps added to the iron melt increases, compared to the FeSi V alloys. Table 6 shows a significant higher yield of Nb for a FeSi Nb alloy compared to FeNb65, both alloys having the same sizing when added to the melt.

[0098] FIG. 4 is a diagram showing dissolution time of FeSi Nb V and FeSi Nb V Mo alloys according to the present invention, compared to standard commercial FeV80 and FeNb65 alloys in an iron melt at a temperature of about 1500? C. The diagram shows dissolution time vs. different sizing of the FeSi Nb V and FeSi Nb V Mo alloys and FeNb65 and FeV80 lumps. The dissolution time of FeV80 and FeNb65 alloys becomes significantly longer as the size of the lumps added to the iron melt increases, compared to the FeSi Nb V and FeSi Nb V Mo alloys.

[0099] The method for preparing the FeSi V and/or Nb alloy according to any of the above embodiments comprises: providing a ferrosilicon alloy in molten state; adding a vanadium oxide containing raw material and/or a niobium oxide containing raw material to the molten ferrosilicon alloy; mixing and reacting the molten ferrosilicon alloy and vanadium oxide from the vanadium oxide containing raw material and/or niobium oxide from the niobium oxide containing raw material, thereby forming a melt of FeSi V and/or Nb alloy and slag; separating the slag from the said melt of FeSi V and/or Nb alloy, optionally adjusting the composition of the elements according to the first aspect; and solidifying or casting the molten FeSi V and/or Nb alloy.

[0100] The following detailed description of the method of producing FeSi V and/or Nb alloy applies to any of the above-described embodiments of the FeSi V and/or Nb alloy according to the present invention.

[0101] The reaction between the molten ferrosilicon alloy and the vanadium oxide and/or the niobium oxide is fast allowing high productivity. The method for preparing the FeSi V and/or Nb alloy can be performed in a ladle, or in any similar suitable vessel such as a crucible or a melting pot including any kind of furnaces, to hold the molten ferrosilicon. Hence, there is no need of heating by supplying external energy such as using a furnace. The temperature of the ferrosilicon melt before addition of the vanadium oxide containing raw material and/or the niobium oxide containing raw material should be from about 1400 to about 1700? C. The present method for producing the FeSi V and/or Nb alloy leads to a high V and/or Nb-yield from the vanadium oxide (e.g. vanadium pentoxide) and/or niobium oxide (e.g. niobium oxide) into the FeSi V and/or Nb alloy, compared with conventional methods for producing ferrovanadium alloys, FeV and ferroniobium alloys, FeNb. Compared to conventional FeV and FeNb production, the present method is elegant and cost efficient.

[0102] The molten ferrosilicon alloy can be provided directly from a reduction furnace, typically a submerged arc furnace (SAF) wherein the ferrosilicon alloy is as-produced from raw materials according to conventional method or from an alloying station where the elements from the first aspect except for vanadium and/or niobium are alloyed in a ferrosilicon provided directly from a reduction furnace. Alternatively, the molten ferrosilicon alloy can be provided by remelting a charge of one or more ferrosilicon alloys, possibly refined or already alloyed with elements from the first aspect except for vanadium and/or niobium, or a combination of as-produced ferrosilicon alloy and a solidified ferrosilicon that is brought into molten state by any suitable heating means.

[0103] According to some embodiments of the method, the starting ferrosilicon alloy can be a mix of several ferrosilicon alloys with different compositions. For example, it can be a mix of ferrosilicon and ferrosilicon manganese or ferrosilicon chromium or ferrosilicon zirconium or ferrosilicon barium.

[0104] According to the method, the vanadium oxide containing raw material, e.g. V.sub.2O.sub.5, and/or niobium oxide containing raw material, e.g. Nb.sub.2O.sub.5 is added to the molten ferrosilicon alloy. The vanadium oxide containing raw material and/or the niobium oxide containing raw material may be added in an amount (by weight) providing essentially the target amount of elemental vanadium and/or niobium (by weight) in the FeSi V and/or Nb alloy. The method for adding the vanadium oxide containing raw material and/or the niobium oxide containing raw material is not critical, and may be performed in any convenient manner.

[0105] The vanadium oxide-containing raw material can be one or more vanadium oxide phases, such as vanadium (II) oxide, vanadium (III) oxide, vanadium (IV) oxide, vanadium (V) oxide, and/or other non-principal oxides of vanadium. The vanadium oxide is preferably vanadium (V) oxide (V.sub.2O.sub.5) and/or vanadium (III) oxide, V.sub.2O.sub.3, which are the most, used vanadium oxides in industrial applications. The vanadium oxide containing raw material may also comprise industrial waste materials or ores comprising vanadium oxide.

[0106] The niobium containing raw material can be one or more niobium oxide phases, such as niobium (II) oxide, niobium (III) oxide, niobium (IV) oxide, niobium (V) oxide, and/or other non-principal oxides of niobium. The niobium oxide is preferably niobium (V) oxide (Nb.sub.2O.sub.5) and/or niobium (III) oxide, Nb.sub.2O.sub.3, which are the most, used niobium oxides in industrial applications. The niobium oxide containing raw material may also comprise industrial waste materials or ores comprising niobium oxide.

[0107] The reduction reaction of the vanadium oxide and/or the niobium oxide leads to the formation of oxide compounds, generally denoted slags, mainly comprising aluminium oxide, silicon oxide and calcium oxide. A slag modifying compound can be added to the ferrosilicon melt to modify the slag formed during the reaction. The slag modifying compound can be CaO and/or MgO, and can be added in an amount of about 0.5-30 wt % of the final alloy, based on the total amount of ferrosilicon alloy. The necessary amount is based on the amount of vanadium oxide and/or niobium oxide to be added. The slag modifying compound can be added before or during the addition of the vanadium oxide containing raw material and/or the niobium oxide containing raw material. The slag composition is modified in a way to have a low viscosity and low melting slag to allow good slag/metal contact during the reduction reaction. Additionally, it can be modified for good metal/slag separation before casting. The slag, both produced during the reaction and added, will float on the melt, such that any formed waste and slag compounds formed during the reaction will accumulate in the layer of slag floating on the top of the melt.

[0108] The starting ferrosilicon alloy for the production of the FeSi V and/or Nb alloy should have a general composition of 40-90 wt % Si; up to 0.5 wt % C; 0.01-7 wt % Al; up to 6 wt % Ca; up to 1.5 wt % Ti; up to 15 wt % Mn; up to 10 wt % Cr; up to 10 wt % Zr; up to 15 wt % Ba; up to 0.3 wt % P; up to 0.5 wt % S; the balance being Fe and incidental impurities.

[0109] According to some embodiments of the method, the amount of Si in the starting ferrosilicon alloy is 70-80 wt %. According to some embodiments of the method, the amount of Si in the starting ferrosilicon alloy is 60-70 wt %. According to some embodiments of the method, the amount of Si in the starting ferrosilicon alloy is 40-55 wt %.

[0110] As-produced ferrosilicon alloys comprises small amounts of Al from the raw materials, typically in an amount of up to 1.5 wt %. The starting ferrosilicon alloy of the present invention may comprise up to 2 wt % Al; e.g, 0.01-2 wt % Al. When the vanadium oxide containing raw material and/or the niobium oxide containing raw material is added to the molten ferrosilicon alloy, the metallic Al present in the molten ferrosilicon reacts with the oxygen of the vanadium oxide and/or the niobium oxide reducing the vanadium and/or niobium, resulting in pure V and/or Nb and heat. Si in the molten ferrosilicon alloy will also react with the oxygen of the vanadium oxide and/or the niobium oxide, resulting in reduction of vanadium oxide to elemental V and/or niobium oxide to elemental Nb. Si is less reactive than Al in the present mixture, therefore, essentially all Al present in the ferrosilicon alloy will react with the oxygen of the vanadium oxide and/or the niobium oxide, resulting in a very low amount of aluminium in the produced FeSi V and/or Nb alloy. Calcium is also a common element in ferrosilicon alloys, generally in an amount of up to about 1.5 wt %. Ca present in the molten ferrosilicon alloy will also react with the oxygen of the vanadium oxide and/or the niobium oxide resulting in pure V and/or Nb and heat.

[0111] Additional aluminium can be added to the molten ferrosilicon alloy, to increase the amount of Al contained in the melt available for reducing the vanadium oxide and/or the niobium oxide. This may especially be relevant when producing FeSi V and/or Nb alloy with a high amount of vanadium and/or niobium, such as from FeSi V and/or Nb with a V and/or Nb amount of 10 wt % (FeSi V and/or Nb 10); up to FeSi V and/or Nb 20; up to up to FeSi V and/or Nb 30 or even up to FeSi V and/or Nb 40, while keeping the amount of silicon in the FeSi V and/or Nb alloy in the upper range. If additional aluminium is added to the ferrosilicon melt, the addition can be made before, during or after, preferably before or during, the addition of the vanadium oxide containing raw material and/or the niobium oxide containing raw material. Metallic aluminium may be added in an amount of up to about 10 wt %, or up to about 5 wt %, or up to about 1 wt %, based on the total amount of ferrosilicon and vanadium oxide and/or niobium oxide.

[0112] The molten ferrosilicon alloy is preferably stirred during the addition of the vanadium oxide containing raw material and/or the niobium oxide containing raw material, and any added aluminium and/or slag modifying compound, and during the reduction reaction in order to ensure contact of the V and/or Nb oxides and metal. The melt is conveniently stirred by mechanical stirring and/or gas stirring means generally known in the field.

[0113] The slag can be separated before or during casting of the molten ferrosilicon vanadium and/or niobium alloy. The FeSi V and/or Nb alloy is casted, and solidified according to generally known methods in the field. The solidified casted metal may be crushed and graded in size fractions adapted for different applications areas. The solidified casted FeSi V and/or Nb may also be agglomerated or in the form of blocks.

[0114] The present FeSi V and/or Nb alloy may be used as an additive in the production of vanadium and/or niobium containing cast iron.

[0115] According to some embodiments, the FeSi V and/or Nb alloy can be alloyed further with additional elements Mo, Cu, Cr, Ni, Mg, Al, Ba, Ca, Mn, Zr, La and/or Ce and/or misch metal, Sr, Bi, Sb according to standard procedures for the production of foundry additives.

[0116] According to some embodiments, foundry additives comprising up to 10 wt % Mo; up to 5 wt % Cr; up to 3 wt % Cu; up to 3 wt % Ni; up to 20 wt % Mg; 0.01 to 7 wt % Al; up to 13 wt % Ba; 0.01 to 7 wt % Ca; up to 13 wt % Mn; up to 8 wt % Zr; up to 12 wt % La and/or Ce and/or misch metal; up to 5 wt % Sr; up to 3 wt % Bi; up to 3 wt % Sb; up to 1.5 wt % Ti; balance Fe and incidental impurities, can also be used as a starting ferrosilicon alloy.

[0117] The granulated alloys can be packed or mixed with other alloys and packed in for example a cored wire. Alloyed with additional elements the ferrosilicon based vanadium and/or niobium alloy can be used as a preconditioner, as a cover material in a ladle nodularising treatment, as a nodulariser, as an inoculant either crushed, with or without a coating, or as an insert, such as a cast block or an agglomeration of powder material. Any type of ferrosilicon based vanadium and/or niobium alloy, further alloyed or coated with other elements, or not, can be used in cored wire.

[0118] A method for production of cast iron comprising adding a FeSi V and/or Nb alloy comprising 15-80 wt % Silicon (Si); 0.5-40 wt % Vanadium (V) and/or Niobium (Nb); up to 10 wt % Molybdenum (Mo); up to 5 wt % Cr; up to 3 wt % Cu; up to 3 wt % Ni; up to 20 wt % Magnesium (Mg); 0.01 to 7 wt % Aluminium (Al); up to 13 wt % Barium (Ba); 0.01 to 7 wt % Calcium (Ca); up to 12 wt % Manganese (Mn); up to 8 wt % Zirconium (Zr); up to 12 wt % Lanthanum (La) and/or Cerium (Ce), and/or misch metal; up to 5 wt % Strontium (Sr); up to 3 wt % Bismuth (Bi); up to 3 wt % Antimony (Sb); up to 1.5 wt % Ti; balance Fe and incidental impurities. The said method for production of cast iron, comprising adding a FeSi V and/or Nb alloy according to any above-described embodiments.

[0119] It was surprisingly found that an alloy based on ferrosilicon and containing vanadium and/or niobium had a much faster assimilation of vanadium and/or niobium by the iron melt which allows the use of such an alloy further down in the cast iron process as the melting point is potentially lower and the dissolution route different with a higher recovery of vanadium and/or niobium than in prior art solutions. An advantage of being able to add vanadium and/or niobium after tapping from the furnace is the possibility to treat less iron allowing easier transition between grades, avoid over-heating of the iron melt and contamination of the lining in the furnace, even having a high flexibility as to the batch size in alloyed cast iron pieces if added as an element in an inoculant in-stream.

[0120] The possible uses of an alloy based on ferrosilicon and containing vanadium and/or niobium are as FeSi V or FeSi Nb V or FeSi Nb and incidental impurities as part of the charge in the furnace or in an holding furnace without the need of long waiting time nor increased temperature over what is necessary for the foundry process downstream, or added further down in the process. When alloyed with additional elements the ferrosilicon based vanadium and/or niobium alloy can also be used to alloy the melt in a furnace, be used as a preconditioner, as a cover material or as nodulariser in a ladle treatment, as an inoculant either crushed, with or without a coating, or as an insert. Any type of ferrosilicon based vanadium and/or niobium alloy, further alloyed or coated with other elements, or not, can be used in cored wire mixed or not with other alloys or elements.

[0121] Another advantage of such an alloy is the lower density compared to FeV80 or FeNb65. Indeed an alloy with a high density will have a tendency to drop to the bottom of a furnace or a ladle and lead to a segregation in the iron melt if not stirred properly.

[0122] Another advantage of such an alloy is to have one less addition step in the process when the addition of vanadium and/or niobium is combined with the addition of other necessary treatment alloys.

EXAMPLES

Example 1. Production of the Ferrosilicon Containing Vanadium Alloys

[0123] Ten melts for the production of FeSi V alloys according to the present invention were prepared. Two categories of alloys were produced. The first category are ferrosilicon vanadium alloys, the second category alloys are a combination of the advantages of ferrosilicon vanadium alloys with the addition of some of the elements commonly used to treat cast iron melts, both categories are according to the present invention. FeSi V was produced as described in this text using vanadium oxide. For the other alloys, the other elements were added to FeSi V. It was done in two steps; a larger batch of FeSi V was produced and then cast and coarsely crushed, then remelted for the addition of the other elements in smaller batches.

[0124] The following table 1 shows raw material amounts of FeSi75 (lumpy) and V.sub.2O.sub.5 (powder) for three test productions of FeSi V. Additionally, lime (CaO) amounts to modify the slag and the total Al in the system are given. The temperature (T) was set to be above the melting point of FeSi V alloy before V.sub.2O.sub.5 addition. The molten ferrosilicon alloy was stirred during addition of V.sub.2O.sub.5, lime and any aluminium. The produced composition is given in the right part of the table. During tapping it is important for the purity of the produced FeSi V alloy to separate slag and metal.

TABLE-US-00001 TABLE 1 Production of FeSi V alloy Additions (kg) Analyses (wt %) Melt FeSi V.sub.2O.sub.5 CaO Al T (? C.) Si V Fe Al Ca Alloy ID 1 10.0 1.84 1.00 0.01 1565 67.1 9.4 22.8 0.020 <0.1 2 7.94 1.46 0.80 0.11 1588 68.5 10.4 21.6 0.035 <0.1 3 10.0 3.78 2.00 0.28 1585 58.7 19.2 21.4 0.024 <0.1 4 10.0 1.83 1.00 0.06 1620 67.0 9.7 22.8 0.015 <0.1 FeSiV10 5 10.0 3.77 2.0 0.0 1620 58.3 18.1 21.5 0.2 <0.1 FeSiV18 6 8.8 5.3 2.8 0.2 1630 49.7 29.5 17.8 0.3 0.9 FeSiV30** *Al added includes Al from FeSi and Al added separately. **The FeSiV30 alloy contains also 1.5 wt % Cr.

[0125] The following table 2 shows the composition of the ferrosilicon alloys containing vanadium with additional commonly used elements for cast iron melt treatment. A ferrosilicon vanadium alloy was first produced according to the method described above, then different elements were alloyed in the melt and these resulting ferrosilicon vanadium alloys according to the invention are denoted alloys for simplicity reasons.

TABLE-US-00002 TABLE 2 Chemical analysis of the V-containing ferrosilicon alloys produced wt % Alloy 1 Alloy 2 Alloy 3 Alloy 4 Si 56.6 57.4 55.1 55.1 V 15.7 16.4 16.7 17.1 Mg <0.1 0.12 <0.1 3.8 Al 0.76 1.14 1.15 0.47 Ba 1.43 <0.5 <0.5 <0.5 Ca 0.65 1.92 1 0.62 Zr <0.1 2.62 <0.1 <0.1 La <0.1 <0.1 <0.1 0.6 Ce 0.4 0.1 1.7 0.1 Bi <0.1 0.1 <0.1 <0.1

Example 2. Comparison of Dissolution Behavior of FeSi V Alloys Vs. FeV80

[0126] The dissolution behavior of FeSi V alloys was compared to the dissolution behavior of FeV80 in molten iron at a temperature of 1400? C. and 1500? C. The carbon and silicon concentrations in the iron melt were 3.6 wt % and 2.2 wt %, respectively. The dissolution time can be measured with different techniques known from literature. Examples would be connecting a load cell to the ferroalloy and measuring the loss in weight [Gourtsoyannis et al., 1984] or taking samples of the cast iron melt in fixed intervals and analyzing the element content [Argyropoulus, 1983]. The methods in the references are described for the measurement of dissolution time in steel; the same principle can be applied for measuring the dissolution time in an iron melt.

[0127] Reference is made to FIG. 1 showing dissolution time at 1400? C. At 1400? C., pieces of FeV80 of sizes between 7 and 18 mm were monitored for approximately 3 minutes but did not dissolve at all and are thus not represented in the plot. Thus, the dissolution time of FeSi V alloys is much lower than the one for FeV80.

[0128] Reference is made to FIG. 2 where it is seen that the measured dissolution time for FeV80 was 2 times longer for lumps up to 20 mm than dissolution time of FeSiV18 (FeSi V with about 18 wt % V). For bigger sizes of the lumps, the difference would be even higher. 1500? C. is a standard tapping temperature from the furnace and all processes after tapping would be at lower temperature and between 1300? C. and 1400? C. for the inoculation step.

Example 3. Vanadium Yield

[0129] FeSi V alloys were used in the inoculation step during the production of cast iron. The melt was heated in an induction over, treated with a nodulariser before it was poured into six pouring ladles. Prior to pouring, the alloys were added to the bottom of the pouring ladles. All the alloys were crushed to the same size 1-3 mm. The quantity of iron poured in each ladle was the same. The temperature of the iron in the nodulariser ladle just prior to pouring in the pouring ladles was 1424? C. The melt was hold in the pouring ladles for 1 and 5 min then cast into a sand mould. Prior to pouring, a coin was taken for chemical analysis in an ArcSpark-OES spectrometer.

[0130] As can be seen in Table 3, the FeSi V alloys were completely assimilated into the melt after 1 min with a full recovery of vanadium, while the recovery of vanadium from FeV80 was only 63% after 5 min.

TABLE-US-00003 TABLE 3 Vanadium yield Holding time: Holding time: 5 1 min min V V in final V in final addition iron Yield iron Yield Ladle Alloy in wt % (wt %) % (wt %) % 1 FeV 80 0.120 No sample 0.080 63 2 FeSiV 18 0.128 0.134 102* 0.136 103* 3 Alloy 1 0.120 0.133 108* 0.133 107* 4 Alloy 2 0.116 0.128 106* 0.126 104* 5 Alloy 4 0.128 0.125 94 0.125 94 6 FeV 80 0.120 0.056 43 0.080 63 *Values over 100% due to a small variation of the amount of iron poured compared to the target.

Example 4. Production of the Ferrosilicon Containing Niobium Alloys

[0131] Eight melts for the production of FeSi Nb alloys according to the present invention were prepared. Two categories of alloys were produced. The first category are ferrosilicon niobium alloys, the second category alloys are a combination of the advantages of ferrosilicon niobium alloys with the addition of some of the elements commonly used to treat cast iron melts, both categories are according to the present invention. FeSi Nb was produced as described in this text using niobium oxide. For the other alloys, the other elements were added to FeSi Nb. It was done in two steps, a larger batch of FeSi Nb was produced and then cast and coarsely crushed, then remelted for the addition of the other elements in smaller batches.

[0132] The following table 4 shows raw material amounts of FeSi75 and Nb.sub.2O.sub.5 (in fine powder form) for three test productions of FeSi Nb. Additionally, lime (CaO) amounts to modify the slag and the total Al in the system are given. The temperature (T) was set to be above the melting point of FeSi Nb alloy before Nb.sub.2O.sub.5 addition. The molten ferrosilicon alloy was stirred during addition of Nb.sub.2O.sub.5, lime and any aluminium. The produced composition is given in the right part of the table. During tapping it is important for the purity of the produced FeSi Nb alloy to separate slag and metal.

TABLE-US-00004 TABLE 4 Production of FeSi Nb alloy Additions (kg) Analyses (wt %) Melt FeSi N.sub.2O.sub.5 Lime, Al added* T (? C.) Si Nb Fe Al Ca Name 1 9 1.41 0.57 0.22 1600 70 8.9 21 0.25 0.08 FeSiNb10 2 9 3.09 1.23 0.47 1650 58 19.0 22 0.29 0.13 FeSiNb20 3 9 5.12 2.04 0.78 1700 47 31.9 21 0.35 0.11 FeSiNb30 *Al added includes Al from FeSi and Al added separately

[0133] The following table 5 shows the composition of the ferrosilicon alloys containing niobium with additional commonly used elements for cast iron melt treatment. A ferrosilicon niobium alloy with target Nb level of 30 wt % was first produced according to the method described above, then different elements were alloyed in the melt and these resulting ferrosilicon niobium alloys according to the invention are denoted alloys for simplicity reasons.

TABLE-US-00005 TABLE 5 Chemical analysis of the Nb-containing ferrosilicon alloys produced. wt % Alloy 5 Alloy 6 Alloy 7 Alloy 8 Alloy 9 Si 48.8 49.5 51.5 48.5 47.4 Nb 28.5 23.7 26.0 29.3 27.2 Al 0.93 3.7 1.9 1.6 4.71 Ba <0.5 <0.5 <0.5 0.18 <0.5 Ca 1.7 2.3 2.7 1.9 1.35 Zr <0.05 3.2 <0.05 0.16 0.97 La <0.1 <0.1 <0.1 <0.1 <0.1 Ce <0.05 <0.05 <0.05 <0.05 <0.05 Sr 1.2 <0.02 <0.02 <0.02 1.27 Ti <0.5 <0.5 <0.5 0.9 <0.5

Example 5. Comparison of Dissolution Behavior of FeSi Nb Alloys Vs. FeNb65

[0134] The dissolution behavior of FeSi Nb alloys was compared to the dissolution behavior of FeNb65 in molten iron at a temperature of 1500? C. The carbon and silicon concentrations in the iron melt were 3.6 wt % and 2.2 wt %, respectively.

[0135] As can be seen in FIG. 3, the dissolution time of the FeSi Nb alloys is shorter than the one of FeNb65. 1500? C. is a standard tapping temperature from the furnace and all processes after tapping would be at lower temperature and between 1300? C. and 1400? C. for the inoculation step. At lower temperature, the higher dissolution time of FeNb65 between the different alloys would be even clearer.

Example 6. Niobium Yield

[0136] Nb is normally added to cast iron by FeNb by addition to the furnace due to the high melting point. The purpose of having Nb as part of a FeSi alloy is to have an alloy with lower melting point, which could facilitate addition later in the process. This was tested out by adding Nb-containing alloys in the inoculation step during production of cast iron. The addition rate of the different Nb-containing alloys was adjusted to deliver the same amount of Nb to the iron, in this case 0.20 wt %. The trial was also done at two temperatures; 1500? C. and 1440? ? C. to check that the yield was not a problem at lower temperatures. A tapping temperature of 1500? C. means a peak temperature of around 1420? C. for dissolution of the Nb-containing alloys, while a tapping temperature of 1440? C. means a peak temperature of around 1350? C. for dissolution of the Nb-containing alloys. The alloys were added in the bottom of pouring ladles and hold for 1 min before casting. Sizing of the alloys was the same for all pouring ladles in both trials, 1-3 mm.

[0137] The trial set up for testing with tapping temperature of 1500? C. can be seen in table 6 below.

TABLE-US-00006 TABLE 6 Trial set up for testing out Nb-yield with tapping temperature of 1500? C. wt % Nb Target Actual Yield HV1 Alloy in alloy Addition wt % Nb wt % Nb Nb % 11 FeNb ?65 0.3 wt %-60 g 0.2 0.027 8 12 FeSiNb20 19 1.0 wt %- 0.19 0.164 81 200 g 13 FeSiNb30 31 0.63 wt %- 0.2 0.176 83 126 g 14 Alloy 8 29 0.88 wt %- 0.26 0.219 80 176 g 15 Alloy 6 24 0.78 wt %- 0.18 0.182 95 156 g 16 Alloy 5 29 0.80 w t%- 0.26 0.219 80 160 g

[0138] The trial was repeated for FeNb, FeSiNb30 and Alloy 8 with a lower tapping temperature; 1440? C. and the trial set is shown in table 7 below.

TABLE-US-00007 TABLE 7 Trial set up for testing out Nb-yield with tapping temperature of 1440? C. wt Target Actual Yield HV2 Alloy % Nb Addition wt % Nb wt % Nb Nb % 21 FeNb ?65 0.30 wt %- 0.2 0.042 16% 60 g 22 Alloy 8 29 0.88 wt %- 0.26 0.211 77% 176 g 23 FeSiNb30 30 0.63 wt %- 0.2 0.145 69% 126 g

[0139] As can be seen from the results in table 6 and 7 a considerable higher yield for Nb was achieved with the FeSi alloys with Nb compared to the FeNb alloy. For the FeSi-based Nb-containing alloys, an Nb-yield above 80% is achieved at the tapping temperature of 1500? C. while only a yield of 8% is achieved with FeNb. At the lower tapping temperature of 1440? C. the Nb-yield of the FeSi alloys with Nb decreases to around 70% while the Nb-yield of 16% is observed with FeNb.

Example 7. Production of the Ferrosilicon Containing Niobium and Vanadium Alloys, and Niobium, Vanadium and Molybdenum Alloys

[0140] One melt for the production of FeSi V Nb alloy according to the present invention was prepared. The following table 8 shows raw material amounts of FeSi75, V.sub.2O.sub.5 and Nb.sub.2O.sub.5.

[0141] Additionally, lime (CaO) amounts to modify the slag and the total Al in the system are given. The temperature (T) was set to be above the melting point of FeSi V Nb alloy before V.sub.2O.sub.5 and Nb.sub.2O.sub.5 addition. The molten ferrosilicon alloy was stirred during addition of V.sub.2O.sub.5, Nb.sub.2O.sub.5, lime and any aluminium. The produced composition is given in the right part of the table. During tapping, it is important for the purity of the produced FeSi V Nb alloy to separate slag and metal.

[0142] An additional alloy was made by adding FeMo65 in addition to vanadium and niobium oxide to obtain a FeSi V Nb Mo alloy. FeMo65 has 65 wt % Mo. The raw material amounts used for the production and the composition of the FeSi V Nb Mo alloy are shown in Table 9.

TABLE-US-00008 TABLE 8 Production and composition of FeSi V Nb alloy Additions (kg) Analyses (wt %) Melt FeSi V.sub.2O.sub.5 N.sub.2O.sub.5 Lime Al added* T (? C.) Si V Nb Fe Al Ca 1 9.0 1.93 1.51 1.68 0.44 1700 57.0 8.8 10.6 23.4 0.12 0.03

TABLE-US-00009 TABLE 9 Production and composition of FeSi V Nb Mo alloy Additions (kg) FeMo T Analyses (wt %) Melt FeSi V.sub.2O.sub.5 N.sub.2O.sub.5 Lime Al 65 (? C.) Si V Nb Mo Fe Al Ca 1 9.0 1.93 1.51 1.68 0.44 0.77 1700 54.2 8.4 10.1 4.8 22.2 0.11 0.03

Example 8. Comparison of Dissolution Behavior of FeSi Nb V and FeSi Nb V Mo Alloys Vs. FeNb65 and FeV80

[0143] The dissolution behavior of FeSi Nb V and FeSi Nb V Mo alloys was compared to the dissolution behavior of FeNb65 and FeSiV80 in a bath of iron at a temperature of 1500? C. The carbon and silicon concentrations in the iron melt were 3.6 wt % and 2.2 wt %, respectively. With reference to FIG. 4, it is obvious that the dissolution times of the FeSi Nb V and FeSi Nb V Mo are lower than the ones for FeV80 and FeNb65.

Example 9. Production of FeSi V from FeSiCr/FeSiMn

[0144] Starting from FeSi alloys comprising Mn and Cr as alloying elements with Mn or Cr content of 5 wt %, will result in FeSi V alloys with compositions as indicated in table 10 below.

TABLE-US-00010 TABLE 10 Amounts FeSiMn/FeSiCr, vanadium oxide, lime and resulting alloy compositions from adding V.sub.2O.sub.5 into FeSiMn or FeSiCr. Additions FeSiCr/FeSiMn alloy Si Fe Mn Cr Resulting alloy (wt %) wt wt wt wt Lime V.sub.2O.sub.5 % % % % % % % % % kg kg kg Kg Si V Fe Mn Cr 70 25 5 0 9.7 1 1.8 10 60.9 10 24 4.8 0.0 70 25 5 0 9.4 2 3.6 10 51.9 20 23 4.7 0.0 69 26 0 5 9.7 1 1.8 10 60.9 10 24 0.0 4.8 69 26 0 5 9.4 2 3.6 10 51.9 20 23 0.0 4.7

[0145] A further trial for the production of FeSi V alloys according to the present invention using FeSiMn as a raw material was prepared. The following table 11 shows raw material amounts of FeSiMn and V.sub.2O.sub.5 for two test productions of FeSi V. Additionally, lime (CaO) amounts to modify the slag and the total Al in the system are given. The molten alloy was stirred during addition of V.sub.2O.sub.5, lime and any aluminium. The produced composition is given in the right part of table 11.

TABLE-US-00011 TABLE 11 Amounts of FeSiMn, lime, aluminum, V.sub.2O.sub.5. Analyses of produced alloy compositions. Additions FeSiCr/FeSiMn alloy Analyses Si Fe Mn Cr Si V Fe Mn Cr wt wt wt wt Lime V.sub.2O.sub.5 Al T wt wt wt wt wt % % % % kg kg kg kg (? C.) % % % % % 63 21 14 9.7 1.0 1.8 0.1 1600 56 10 19 13

Example 10. Density Measurement of Selected Alloys

[0146] Table 12 shows the measured densities for selected alloys. As it can be seen from the table, the densities of the FeSi V Nb alloys according to the invention are considerably lower than the densities of FeV80 and FeNb65.

TABLE-US-00012 TABLE 12 Alloy densities Material Density (g/cm.sup.3) FeV80 6.02 FeSi V10 3.43 FeSi V18 3.87 FeSi V30 4.55 Alloy 1 3.76 Alloy 2 3.79 Alloy 4 3.07 FeNb65 7.84 FeSi Nb10 3.33 FeSi Nb20 3.64 FeSi Nb30 4.12 FeSi V Nb 4.11 FeSi V Nb Mo 4.33 Alloy 8 4.02

[0147] The person skilled in the art realizes that the present invention is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study the disclosure, and the appended claims.