Addition agent for adding vanadium to iron base alloys

Abstract

Addition of vanadium to molten iron-base alloys using an agglomerated mixture of V.sub.2 O.sub.3 and calcium-bearing reducing agent.

Description

The present invention is related to the addition of vanadium to molten iron-base alloys, e.g., steel. More particularly, the present invention is directed to an addition agent comprising V.sub.2 O.sub.3 and a calcium-bearing reducing agent.

It is a common requirement in the manufacture of iron base alloys, e.g., steel, to make additions of vanadium to the molten alloy.

Previous commercial techniques have involved the use of ferrovanadium alloys and vanadium and carbon, and vanadium, carbon and nitrogen containing materials as disclosed in U.S. Pat. No. 3,040,814.

Such materials, while highly effective in many respects, require processing techniques that result in aluminium, carbon and nitrogen containing additions and consequently, cannot be satisfactorily employed in all applications, e.g., the manufacture of pipe steels and quality forging grades of steel.

Pelletized mixtures of V.sub.2 O.sub.5 plus aluminum; V.sub.2 O.sub.5 plus silicon plus calcium-silicon alloy; V.sub.2 O.sub.5 plus aluminum plus calcium-silicon, and "red-cake" plus 21%, 34% or 50% calcium-silicon alloy have been previously examined as a source of vanadium in steel by placing such materials on the surface of molten steel. The "red-cake" used was a hydrated sodium vanadate containing 85% V.sub.2 O.sub.5, 9% Na.sub.2 O and 2.5% H.sub.2 O. The results were inconclusive, probably due to oxidation and surface slag interference.

It is therefore an object of the present invention to provide a vanadium addition for iron base alloys, especially a vanadium addition that does not require energy in preparation and which enables, if desired, the efficient addition of the vanadium metal constituent without adding carbon or nitrogen.

Other objects will be apparent from the following descriptions and claims taken in conjunction with the drawing wherein:

FIG. 1 is a graph showing the effect of particle sizing on vanadium recovery and

FIGS. 2 (a)-(c), show electron probe analyses of steel treated in accordance with the present invention.

The vanadium addition agent of the present invention is a blended, agglomerated mixture consisting essentially of V.sub.2 O.sub.3 (at least 95% by weight V.sub.2 O.sub.3) and a calcium-bearing reducing agent. The mixture contains about 55 to 65% by weight of V.sub.2 O.sub.3 and 35% to 45% by weight of calcium-bearing reducing agent. In a preferred embodiment of the present invention, the reducing agent is a calcium-silicon alloy, about 28-32% by weight Ca and 60-65% by weight Si, containing primarily the phases CaSi.sub.2 and Si; the alloy may advantageously contain up to about 8% by weight iron, aluminum, barium, and other impurities incidental to the manufacturing process, i.e., the manufacture of calcium-silicon alloy by the electric furnace reduction of CaO and SiO.sub.2 with carbon. (Typical analyses: Ca 28-32%, Si 60-65%, Fe 5.0%, Al 1.25%, Ba 1.0%, and small amounts of impurity elements.)

In the practice of the present invention a blended, agglomerated mixture of V.sub.2 O.sub.3 and calcium-silicon alloy is prepared in substantially the following proportions: 50% to 70%, preferably 55% to 65% by weight V.sub.2 O.sub.3 and 30% to 50%, preferably 35% to 45% by weight calcium-silicon alloy. The particle size of the calcium-silicon alloy is predominantly (more than 90%) 8 mesh and finer (8M.times.D) and the V.sub.2 O.sub.3 is sized predominantly (more than 90%) 100 mesh and finer (100M.times.D).

The mixture is thoroughly blended and thereafter agglomerated, e.g., by conventional compacting techniques so that the particles of the V.sub.2 O.sub.3 and reducing agent such as calcium-silicon alloy particles are closely associated in intimate contact. The closely associated agglomerated mixture is added to molten steel where the heat of the metal bath and the reducing power of the reducing agent are sufficient to activate the reduction of the V.sub.2 O.sub.3. The metallic vanadium generated is immediately integrated into the molten metal.

It is important that the addition agent of the present invention be rapidly immersed in the molten metal to minimize any reaction with oxygen in the high temperature atmosphere above the molten metal which would oxidize the calcium-bearing reducing agent. Also, contact of the addition agent with any slag or slag-like materials on the surface of the molten metal should be avoided so that the reactivity of the addition is not diminished by coating or reaction with the slag. This may be accomplished by several methods. For example, by plunging the addition agent, encapsulated in a container, into the molten metal or by adding compacted mixture into the pouring stream during the transfer of the molten metal from the furnace to the ladle. In order to ensure rapid immersion of the addition agent into the molten metal, the ladle should be partially filled to a level of about one-quarter to one-third full before starting the addition, and the addition should be completed before the ladle is filled. The CaO and SiO.sub.2 formed when the vanadium oxide is reduced enters the slag except when the steel is aluminum deoxidized. In that case, the CaO generated modifies the Al.sub.2 O.sub.3 inclusions resulting from the aluminum deoxidation practice.

V.sub.2 O.sub.3 (33% O) is the preferred vanadium oxide source of vanadium because of its low oxygen content. Less calcium-bearing reducing agent is required for the reduction reaction on this account and, also a small amount of CaO and SiO.sub.2 is generated upon addition to molten metal.

In addition, the melting temperature of the V.sub.2 O.sub.3 (1970.degree. C.) is high and thus, the V.sub.2 O.sub.3 plus calcium-silicon alloy reduction reaction temperature closely approximates the temperature of molten steel (>1500.degree. C.). Chemical and physical properties of V.sub.2 O.sub.3 and V.sub.2 O.sub.5 are tabulated in Table VI.

The following example further illustrates the present invention.

EXAMPLE

Procedure

Armco iron was melted in a magnesia-lined induction furnace with argon flowing through a graphite cover. After the temperature was stabilized at 1600.degree. C..+-.10.degree. C., the heat was blocked with silicon. Next, except for the vanadium addition, the compositions of the heats were adjusted to the required grade. After stabilizing the temperature at 1600.degree. C..+-.5.degree. C. for one minute, a pintube sample was taken for analyses and then a vanadium addition was made by plunging a steel foil envelope containing the vanadium addition into the molten steel. The steel temperature was maintained at 1600.degree. C..+-.5.degree. C. with the power on the furnace for three minutes after addition of the V.sub.2 O.sub.3 plus reducing agent mixture. Next, the power was shut off and after one minute, pintube samples were taken and the steel cast into a 100-pound, 10.2 cm.sup.2 (4".sup.2) ingot. Subsequently, specimens removed from mid-radius the ingot, one-third up from the bottom, were examined microscopically and analyzed chemically. Some were analyzed on the electron microprobe.

Various mixtures of V.sub.2 O.sub.3 plus reducing agent were added as a source of vanadium in molten steel having different compositions. In Table I, the results are arranged in order of increasing vanadium recoveries for each of the steel compositions. The data in Table II compares the vanadium recoveries for various grades of steel when the vanadium additions were V.sub.2 O.sub.3 plus calcium-silicon alloy (8M.times.D) mixtures compacted under different conditions representing different pressures, and in Table III, when the particle size of the calcium-silicon alloy was the principal variable. In order to more completely characterize the preferred V.sub.2 O.sub.3 plus calcium-silicon alloy addition mixture, the particle size distribution of the commercial grade calcium-silicon alloy (8M.times.D) is presented in Table IV. It may be noted that 67% is less than 12 mesh and 45% less than 20 mesh. As shown in FIG. 1, finer particle size fractions of the calcium-silicon alloy are efficient in reducing the V.sub.2 O.sub.3, however, the 8M.times.D fraction is not only a more economical but also a less hazardous product to produce than the finer fractions.

In some grades of steel, the addition of carbon or carbon and nitrogen is either acceptable or beneficial. Vanadium as well as carbon or carbon plus nitrogen can also be added to these steels by reducing the V.sub.2 O.sub.3 with CaC.sub.2 or CaCN.sub.2 as shown in Table V.

As noted above Table I represents the experimental heats arranged in order of increasing vanadium recoveries for each steel composition. It may be noted that reducing agents such as aluminum and aluminum with various fluxes, will reduce V.sub.2 O.sub.3 in molten steel. However, for all of these mixtures, the vanadium recoveries in the steels were less than 30 percent.

As shown in Table I and FIG. 1, optimum vanadium recoveries were recorded when the vanadium source was a closely associated mixture of 60% V.sub.2 O.sub.3 (100M.times.D) plus 40% calcium-silicon alloy (8M.times.D). It may also be noted in Table I that the vanadium recoveries are independent of the steel compositions. This is particularly evident in Table II where the vanadium recovery from the 60% V.sub.2 O.sub.3 plus 40% calcium-silicon alloy, 8M.times.D, mixtures exceeded 80% in aluminum-killed steels (0.08-0.22% C), semi-killed steels (0.18-0.30%), and plain carbon steels (0.10-0.40% C). Moreover, Table II shows that the vanadium recovery gradually improved when the 60% V.sub.2 O.sub.3 plus 30% calcium-silicon alloy (8M.times.D) was briquetted by a commercial-type process using a binder instead of being packed by hand in the steel foil immersion envelopes. In other words, the close association of the V.sub.2 O.sub.3 plus calcium-silicon alloy mixture that characterizes commercial-type briquetting with a binder improves vanadium recoveries. For example, the heats with the addition methods emphasized by squarelike enclosures in Table II were made as duplicate heats except for the preparation of the addition mixture. In all but one pair of heats, the vanadium recoveries from the commercial-type briquets were superior to tightly packing the mixture in the steel foil envelopes.

The data in Table III show the effect of the particle size of the reducing agent, calcium-silicon alloy, in optimizing the vanadium recoveries. Again, the vanadium recoveries were independent of the steel compositions and maximized when the particle size of the calcium-silicon alloy was 8M.times.D or less as illustrated in the graph of FIG. 1. Although high vanadium recoveries >90%, were measured when the particle size ranges of the calcium-silicon alloy were 150M.times.D and 100M.times.D, the potential hazards and costs related to the production of these size ranges limit their commercial applications. For this reason, 8M.times.D calcium-silicon alloy has optimum properties for the present invention. The particle size distribution of commercial grade 8M.times.D is shown in Table IV.

When small increases in the carbon or carbon-plus-nitrogen contents of the steel are either acceptable or advantageous for the steelmaker, CaC.sub.2 and/or CaCN.sub.2 can be employed as the reducing agent instead of the calcium-silicon alloy. It has been found that commercial grade CaC.sub.2 and CaCN.sub.2 are also effective in reducing V.sub.2 O.sub.3 and adding not only vanadium but also carbon or carbon and nitrogen to the molten steel. The results listed in Table V show the vanadium recoveries and increases in carbon and nitrogen contents of the molten steel after the addition of V.sub.2 O.sub.3 plus CaC.sub.2 and V.sub.2 O.sub.3 plus CaCN.sub.2 mixtures.

Specimens removed from the ingots were analyzed chemically and also examined optically. Frequently, the inclusions in the polished sections were analyzed on the electron microprobe. During this examination, it was determined that the CaO generated by the reduction reaction modifies the alumina inclusions characteristic of aluminum-deoxidized steels. For example, as shown in the electron probe illustrations of FIG. 2 where the contained calcium and aluminum co-occur in the inclusions. Thus, the addition of the V.sub.2 O.sub.3 plus calcium-bearing reducing agent to molten steel in accordance with present invention is not only a source of vanadium but also the calcium oxide generated modifies the detrimental effects of alumina inclusions in aluminum-deoxidized steels. The degree of modification depends on the relative amounts of the CaO and Al.sub.2 O.sub.3 in the molten steel.

In view of the foregoing it can be seen that a closely associated agglomerated mixture of V.sub.2 O.sub.3 and calcium-bearing reducing agent is an effective, energy efficient source of vanadium when immersed in molten steel.

The mesh sizes referred herein are U.S. Screen series.

TABLE I__________________________________________________________________________Vanadium Additives for Steel % V V Source.sup.(1) Reducing Agent.sup.(2) V Recovered Heat % % Particle Addition % V Furnace-Type Steel No. V.sub.2 O.sub.3 Identity Wt. Size Method.sup.(3) Added "3-Min." % C__________________________________________________________________________Low Carbon:0.036-0.05% Al J635 65 Al 32 Powder P 0.25 40.10- 0.12% C +3% 40% Cryolite0.16-0.31% Si Flux +60% CaF.sub.2 (oil)1.50-1.60% Mn J636 67 CaF.sub.2 (Flux) 3 Al 30 Powder P 0.25 10 J639 65 Al 35 7-100M P 0.25 36 (Granules) J637 65 Al 35 Shot P 0.25 52 J647 60 "Hypercal" 40 1/8" P 0.25 64 J645 60 CaSi 40 1/4" P 0.25 72 J676 60 CaSi 40 1/2" P 0.25 76 J644 60 CaSi 40 1/8" P 0.25 80 J641 60 CaSi 40 1/8" P 0.25 80 J619 65 CaSi 35 8M .times. D P 0.13 80 J615 50 CaSi 50 8M .times. D P 0.13 85 J614 55 CaSi 45 8M .times. D P 0.13 87 J620 60 CaSi 40 8M .times. D P 0.13 88 J798 60 CaSi 40 150M .times. D B 0.25 92 J800 60 CaSi 40 8M .times. D BC 0.25 92 J799 60 CaSi 40 100M .times. D B 0.25 96Carbon Steels:0.03-0.07% Al J645 60 CaSi 40 1/8" P 0.20 750.23-0.29% C J672 65 CaC.sub.2 35 1/4" .times. 1/12" P 0.20 760.27-0.33% Si J671 55 CaC.sub.2 45 1/4" .times. 1/12" P 0.20 771.35-1.60% Mn J669 65 CaSi 35 8M .times. D P 0.20 79 J670 70 CaSi 30 8M .times. D P 0.20 81 J657 60 CaC.sub.2 40 1/12" .times. 1/4" P 0.20 83 J656 60 CaSi 40 8M .times. D P 0.20 87 J655 60 CaSi 40 8M .times. D P 0.20 90Carbon Steels:0.04-0.07% Al J678* 60 CaCN.sub.2 40 <325M P 0.20 500.15-0.20% C J677* 65 CaCN.sub.2 35 <325M P 0.20 550.22-0.28% Si J679* 55 CaCN.sub.2 45 <325M P 0.20 601.40-1.50% Mn J680* 50 CaCN.sub.2 50 <325M P 0.20 60 J674 65 CaSi 35 8M .times. D B 0.20 80 J675 60 CaC.sub.2 40 16M .times. D P 0.20 85 J676 65 CaC.sub.2 35 16M .times. D P 0.20 85 J673 60 CaSi 40 8M .times. D B 0.20 85Carbon Steels:0.03-0.07% Al J634 60 CaSi 40 8M .times. D P 0.25 68* 0.080.27-0.33% Si J699 60 CaSi 40 8M .times. D Loose 0.20 81 0.171.35-1.60% Mn J673 60 CaSi 40 8M .times. D B 0.20 85 0.13 J714 60 CaSi 40 8M .times. D P 0.20 86 0.16 J734 60 CaSi 40 8M .times. D BC 0.19 89 0.08 J747 60 CaSi 40 8M .times. D BC 0.21 90 0.10Semi-Killed:0.07-0.12% Si J709 60 CaSi 40 8M .times. D P 0.149 75 0.300.62-0.71% Mn J708 60 CaSi 40 8M .times. D P 0.15 75 0.21 J707 60 CaSi 40 8M .times. D P 0.16 79 0.16 J702 60 CaSi 40 8M .times. D BC 0.15 89 0.38 J735 60 CaSi 40 70M .times. D BC 0.20 90 0.08 J700 60 CaSi 40 8M .times. D BC 0.16 93 0.18 J701 60 CaSi 40 8M .times. D BC 0.16 93 0.25Plain Carbon:0.19-0.29% Si J710 60 CaSi 40 8M .times. D P 0.15 75 0.100.54-0.85% Mn J711 60 CaSi 40 8M .times. D P 0.17 85 0.20 J713 60 CaSi 40 8M .times. D BC 0.17 86 0.38 J706 60 CaSi 40 8M .times. D BC 0.15 88 0.40 J705 60 CaSi 40 8M .times. D BC 0.15 88 0.31 J703 60 CaSi 40 8M .times. D BC 0.15 90 0.11 J712 60 CaSi 40 8M .times. D P 0.18 92 0.29 J704 60 CaSi 40 8M .times. D BC 0.16 92 0.18__________________________________________________________________________ *Presumed erratic result .sup.(1) Vanadium Source: V.sub.2 O.sub.3 >99% pure, 100M .times. D (commercial product, UCC). .sup.(2) Reducing Agents: CaSi Alloy 29.5% Ca, 62.5% Si, 4.5% Fe, trace amounts of Mn, Ba, Al, C, etc. (commercial product, UCC). CaCN.sub.2 >99% pure, 325M .times. D (chemical reagent). CaC.sub.2 Foundry grade, 66.5% CaC.sub.2 (commercial product, UCC) (1/4 .times. 1/12" particle size). Al Powder Alcoa Grade No. 121978. "Hypercal" 10.5% Ca, 39% Si, 10.3% Ba, 20% Al, 18% Fe. ##STR1## *About 10 pounds of metal thrown from the furnace when the V.sub.2 O.sub. + CaCN.sub.2 was plunged. TABLE II__________________________________________________________________________Effect of Packing Density and Steel Compositions on Vanadium RecoveriesVanadium Source: 60% Y.sub.2 O.sub.3 + 40% CaSi (8M .times. D) Composition of Furnace -% V Addition "3 Minute" Pintube (Steel) % VHeat No. Added Method* % C % Si % Al % Mn % V Recovery__________________________________________________________________________ **J634 J620 J673 J714 J699 J655 J656 0.25 0.13 0.20 0.20 0.20 0.20 0.20 P P B P No P P P 0.077 0.085 0.130 0.16 0.17 0.21 0.22 0.24 0.30 0.23 0.275 0.284 0.29 0.32 0.057 0.059 0.074 0.061 0.063 0.055 0.05 1.49 1.51 1.51 1.514 1.609 1.64 1.69 0.16 0.114 0.17 0.172 0.161 0.180 0.17 ##STR2## J734 J747 J700 J707 J701 J708 J702 J709 0.186 0.2052 0.172 0.20 0.172 0.20 0.172 0.20 ##STR3## 0.08 0.10 0.18 0.16 0.25 0.21 0.38 0.30 0.16 0.39 0.069 0.107 0.069 0.106 0.097 0.121 ##STR4## 0.50 0.82 0.657 0.704 0.64 0.704 0.708 0.626 0.165 0.19 0.16 0.158 0.16 0.15 0.153 ##STR5## J703 J710 J704 J711 J705 J712 J706 J713 0.172 0.20 0.172 0.20 0.172 0.20 0.172 0.20 ##STR6## 0.11 0.10 0.18 0.20 0.31 0.29 0.40 0.38 0.21 0.245 0.195 0.287 0.233 0.253 0.224 0.252 ##STR7## 0.543 0.573 0.543 0.616 0.873 0.861 0.831 0.154 0.15 0.159 0.17 0.152 0.183 0.152 0.172 ##STR8##__________________________________________________________________________ *The vanadium additions were made by plunging steel foil envelopes containing the 60% V.sub.2 O.sub.3 + 40% calciumsilicon mixtures into molten steel (1660.degree. C. .+-. 5.degree. C.). The mixtures were place in the envelopes as [1] tightly packed mix (P); [2] not packed (no P); [3 briquets made in a hand press, no binder (B); or [4] commercialtype briquets made on a briquetting machine with a binder (BC). **presumed erratic result TABLE III__________________________________________________________________________Influence of Calcium-Silicon Alloy Particle Size on theRecovery of Vanadium from Vanadium Oxide in Steel V Source CaSI Heat % Particle Addition % V % V No. V.sub.2 O.sub.3 % Size Method* Added Recovered__________________________________________________________________________Low Carbon: 0.036-0.05% Al, 0.10-0.12% C, J798 60 40 150M .times. D B 0.25 92 0.16-0.31% Si, 1.50-1.60% Mn J799 60 40 100M .times. D B 0.25 96 J800 60 40 8M .times. D C 0.25 92 J645 60 40 1/4" P 0.25 72 J646 60 40 1/2" P 0.25 76 J644 60 40 1/8" P 0.25 80 J641 60 40 1/8" P 0.25 80 J640 60 40 8M .times. D P 0.13 88Carbon Steels: 0.04-0.07% Al, 0.23-0.29% C, J654 60 40 1/8" P 0.20 75 0.27-0.33% Si, 1.35-1.60% Mn J656 60 40 8M .times. D P 0.20 87 J655 60 40 8M .times. D P 0.20 90Semi-Killed: 0.19-0.40% Si, J735 60 40 70M .times. D BC 0.195 90 0.60-0.80% Mn, 0.08-0.10% C J747 60 40 70M .times. D BC 0.205 93__________________________________________________________________________ ##STR9## TABLE IV______________________________________Particle Size Distribution ofCalcium-Silicon Alloy (8 Mesh .times. Down)______________________________________ 6 Mesh - Maximum 4% on 8M 33% on 12M 55% on 20M 68% on 32M 78% on 48M 85% on 65M 89% on 100M 93% on 150M 95% on 200M______________________________________ Products of Union Carbide Corporation, Metals Division TABLE V__________________________________________________________________________Vanadium Additives for Steel Containing Carbon or Carbon Plus Nitrogen Reducing Agent.sup.(2) V % V N Heat % Particle Addition % V Recovered % C (ppm)Carbon Steel: No. V.sub.2 O.sub.3.sup.(1) Identity % Size Method.sup.(3) Added Furnace Inc..sup.(4) Inc..sup.(4)__________________________________________________________________________0.03-0.7% Al J672 65 CaC.sub.2 35 1/4" .times. 1/2" P 0.20 76 0.020.23-0.29% C J671 55 CaC.sub.2 45 1/4" .times. 1/2" P 0.20 77 0.030.27-0.33% Si J657 60 CaC.sub.2 40 1/2" .times. 1/4" P 0.20 83 0.031.35-1.60% Mn0.04-0.07% Al J678* 60 CaCn.sub.2 40 <200M P 0.20 50 0.02 1201.15-0.20% C J677* 65 CaCn.sub.2 35 <200M P 0.20 55 0.01 1020.22-0.28% Si J679* 55 CaCn.sub.2 45 <200M P 0.20 60 0.03 1941.40-1.50% Mn J680* 50 CaCN.sub.2 50 <200M P 0.20 60 0.03 225 J675 60 CaC.sub.2 40 16M .times. D P 0.20 85 0.04 J676 65 CaC.sub.2 35 16M .times. D P 0.20 85 0.04__________________________________________________________________________ .sup.(1) V.sub.2 O.sub.3 : >99% pure, 100M .times. D (commercial product, UCC). .sup.(2) CaC.sub.2 : 80% CaC.sub.2, 14% CaO, 2.9% SiO.sub.2, 1.6% Al.sub. O.sub.3 (commercial product, UCC). CaCn.sub.2 : 50% Ca, 15% C, 35% N (chemically pure). .sup.(3) Mixture tightly packed in steel foil envelope and plunged into molten steel 1600.degree. C. .+-. 5.degree. C. .sup.(4) Increase in % C and ppm N in molten steel due to addition of vanadium plus CaC.sub.2 or CaCN.sub.2 mixture ("3minute" pintube samples) *About 10 pounds of metal thrown out of furnace due to violence of the reaction. TABLE VI______________________________________ Comparison of Properties of V.sub.2 O.sub.5 Refer-Property V.sub.2 O.sub.3 V.sub.2 O.sub.5 ence______________________________________Density 4.87 3.36 1Melting Point 1970.degree. C. 690.degree. C. 1PointColor Black Yellow 1Character Basic Amphoteric 2of OxideComposition 68% V + 32% 0 56% V + 44% 0 (Calc.)Free Energy of -184,500 -202,000 cal/mole 3Formation cal/mole(1900.degree. K.)Crystal a.sub.o = 5.45 .+-. 3 A a.sub.o = 4.369 .+-. 5 A 4Structure .alpha. = 54.degree.49' .+-. 8' b.sub.o = 11.510 .+-. 8 A Rnombohedral c.sub.o = 3.563 .+-. 3 A Orthohrombic______________________________________

Claims

1. An addition agent for adding vanadium to molten iron base alloys consisting essentially of an agglomerated, blended mixture of about 50 to 70% by weight of finely divided V.sub.2 O.sub.3 with about 30 to 50% by weight of a finely divided calcium-bearing material selected from the group consisting of calcium-silicon alloy, calcium carbide and calcium cyanamide.

2. An addition agent in accordance with claim 1 wherein said V.sub.2 O.sub.3 is sized predominantly 100 mesh and finer and said calcium-bearing material is sized predominantly 8 mesh and finer.

3. An addition agent in accordance with claim 1 wherein said calcium-bearing material is calcium-silicon alloy.

4. An addition agent in accordance with claim 1 wherein said calcium-bearing material is calcium carbide.

5. An addition agent in accordance with claim 1 wherein said calcium-bearing material is calcium-cyanamide.

6. A method for adding vanadium to molten iron-base alloy which comprises immersing in molten iron-base alloy an addition agent consisting essentially of an agglomerated, blended mixture of about 50 to 70% by weight of finely divided V.sub.2 O.sub.3 with about 30 to 50% by weight of a finely divided calcium-bearing material selected from the group consisting of calcium-silicon alloy, calcium carbide and calcium cyanamide.

7. A method in accordance with claim 6 wherein said V.sub.2 O.sub.3 is sized predominantly 100 mesh and finer and said calcium-bearing material is sized predominantly 8 mesh and finer.

8. A method in accordance with claim 6 wherein said calcium-bearing material is calcium-silicon alloy.

9. A method in accordance with claim 6 wherein said calcium-bearing material is calcium carbide.

10. A method in accordance with claim 6 wherein said calcium-bearing material is calcium-cyanamide.

11. A method for adding vanadium to molten iron-base alloy which comprises preparing an addition agent consisting essentially of an agglomerated, blended mixture of about 50 to 70% by weight of finely divided V.sub.2 O.sub.3 with about 30 to 50% by weight of a finely divided calcium-bearing material selected from the group consisting of calcium-silicon alloy, calcium carbide and calcium cyanamide, and then rapidly immersing the addition agent into the molten iron-base alloy so as to avoid any significant exposure of the addition agent to oxidizing conditions.

12. A method in accordance with claim 11 wherein the addition agent is immersed into the molten iron-base alloy in a manner such as to avoid substantial contact with any slag-like materials present on the surface of the molten metal.