Addition agent for adding vanadium to iron base alloys

This application is a continuation-in-part of my earlier filed co-pending application Ser. No. 249,503 filed Mar. 31, 1981, now U.S. Pat. No. 4,396,425, issued on Aug. 2, 1983.

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 V₂ O₃ 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 V₂ O₅ plus aluminum; V₂ O₅ plus silicon plus calcium-silicon alloy; V₂ O₅ plus aluminium 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% V₂ O₅, 9% Na₂ O and 2.5% H₂ 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 constitutent without adding carbon or nitrogen.

Another object of the present invention is to provide such a vanadium addition which, due to its low density, is amenable to pneumatic injection into a molten iron base alloy with a carrier gas and which makes possible high recoveries and absolute control of processing conditions.

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

FIG. 2 (a)-(c), show electron probe analysis 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 V₂ O₃ (at least 95% by weight V₂ O₃) and a calcium-bearing reducing agent. The mixture contains about 55 to 65% by weight of V₂ O₃ 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 CaSi₂ 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 SiO₂ with carbon. (Typical analysis: 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 V₂ O₃ and calcium-silicon alloy is prepared in substantially the following proportions: 50% to 70%, preferably 55% to 65% by weight V₂ O₃ 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×D) and the V₂ O₃ is sized predominantly (more than 90%) 100 mesh and finer (100M×D).

The mixture is thoroughly blended and thereafter agglomerated, e.g., by conventional compacting techniques so that the particles of the V₂ O₃ 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 V₂ O₃. 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 SiO₂ 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 O₃ inclusions resulting from the aluminum deoxidation practice.

Another method of adding the addition agent to the molten iron-base alloy is to inject the addition agent into the molten alloy with a carrier gas. The carrier gas may be argon or nitrogen, for example. In addition to minimizing reaction with oxygen and avoiding contact with slag or slag-like material, this method offers several advantages, for example, when compared to ferrovanadium addition, the V₂ O₃ -CaSi mixture is about two and one-half times less dense than ferrovanadium. This is shown by the data below.

______________________________________Vanadium Addition            Apparent Density______________________________________Briquets, 60% V2 O3 +            2.50 gm/cc40% CaSi60% FeV          6.35 gm/cc80% FeV          6.29 gm/cc______________________________________

Because the vanadium additive is less dense, the flow rate of the carrier gas-additive mixture can be significantly reduced, i.e., the weight of the heavier ferrovanadium is not a limiting factor. Therefore, greater control of the processing conditions is possible. In addition, the particle size of the additive mixture can be readily altered to suit the injection process by forming the mixture to a predetermined particle size during its preparation. This also provides for increased flexibility in the injection process. Typically, after its preparation as described above, the additive mixture should be reduced to a particle size in the range of from about 10 mesh up to about one-half inch. The concentration of the particles in the carrier gas may of course be varied over a wide range depending upon the particular particle size chosen.

V₂ O₃ (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 smaller amount of CaO and SiO₂ is generated upon addition to molten metal.

In addition, the melting temperature of the V₂ O₃ (1970° C.) is high and thus, the V₂ O₃ plus calcium-silicon alloy reduction reaction temperature closely approximates the temperature of molten steel (>1500° C.). Chemical and physical properties of V₂ O₃ and V₂ O₅ 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° C.±10° 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° C.±5° C. for one minute, a pintube sample was taken for analysis 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° C.±5° C. with the power on the furnace for three minutes after addition of the V₂ O₃ 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 ² (4 in)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 microprote.

Various mixtures of V₂ O₃ 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 V₂ O₃ plus calcium-silicon alloy (8M×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 V₂ O₃ plus calcium-silicon alloy addition mixture, the particle size distribution of the commercial grade calcium-silicon alloy (8M×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 V₂ O₃, however, the 8M×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 V₂ O₃ with CaC₂ or CaCN₂ 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 V₂ O₃ in molten steel. However, for all of these mixtures, the vanadium recoveries in the steels were less than 80 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% V₂ O₃ (100M×D) plus 40% calcium-silicon alloy (8M×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% V₂ O₃ plus 40% calcium-silicon alloy, 8M×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% V₂ O₃ plus 40% calcium-silicon alloy (8M×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 V₂ O₃ 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×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×D and 100M×D, the potential hazards and costs related to the production of these size ranges limit their commercial applications. For this reason, 8M×D calcium-silicon alloy has optimum properties for the present invention. The particle size distribution of commercial grade 8M×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 steel maker, CaC₂ and/or CaCN₂ can be employed as the reducing agent instead of the calcium-silicon alloy. It has been found that commercial grade CaC₂ and CaCN₂ are also effective in reducing V₂ O₃ 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 V₂ O₃ plus CaC₂ and V₂ O₃ plus CaCN₂ 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, see the electron probe illustrations of FIG. 2 where the contained calcium and aluminum co-occur in the inclusions. Thus, the addition of the V₂ O₃ 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 Al₂ O₃ in the molten steel.

In view of the foregoing it can be seen that a closely associated agglomerated mixture of V₂ O₃ and calcium-bearing reducing agent is an effective, energy efficient source of vanadium when immersed in molten steel.

The mesh sizes referred herein are United States Screen series.

                                  TABLE I__________________________________________________________________________Vanadium Additives for Steel                                      % V       Source.sup.(1)             Reducing Agent.sup.(2)                             V        Recovered   Heat       %            %  Particle                             Addition                                  % V Furnace -Type Steel   No. V2 O3             Identity                    Wt.                       Size  Method.sup.(3)                                  Added                                      "3-Min."                                            % C__________________________________________________________________________Low Carbon:0.036-0.5% Al   J635       65    Al     32 Powder                             P    0.25                                       40.10-0.12% C      +3%   40% Cryolite0.16-0.31% Si     Flux  +60% CaF2 (oil)1.50-1.60% Mn   J636       67    CaF2 (Flux)                     3             Al     30 Powder                             P    0.25                                      10   J639       65    Al     35 7-100 M                             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 8 M × D                             P    0.13                                      80   J615       50    CaSi   50 8 M × D                             P    0.13                                      85   J614       55    CaSi   45 8 M × D                             P    0.13                                      87   J620       60    CaSi   40 8 M × D                             P    0.13                                      88   J798       60    CaSi   40 150 M × D                             B    0.25                                      92   J800       60    CaSi   40 8 M × D                             BC   0.25                                      92   J799       60    CaSi   40 100 M × D                             B    0.25                                      96Carbon Steels:   J654       60    CaSi   40 1/8"  P    0.20                                      750.03-0.07% Al   J672       65    CaC2                    35 1/4" × 1/12"                             P    0.20                                      760.23-0.29% C   J671       55    CaC2                    45 1/4" × 1/12"                             P    0.20                                      770.27-0.33% Si   J669       65    CaSi   35 8 M × D                             P    0.20                                      791.35-1.60% Mn   J670       70    CaSi   30 8 M × D                             P    0.20                                      81   J657       60    Ca2                    40 1/12" × 1/4"                             P    0.20                                      83   J656       60    CaSi   40 8 M × D                             P    0.20                                      87   J655       60    CaSi   40 8 M × D                             P    0.20                                      90Carbon Steels:    J678*       60    CaCN2                    40 <325 M                             P    0.20                                      500.04-0.07% Al    J677*       65    CaCN2                    35 <325 M                             P    0.20                                      550.15-0.20% C    J679*       55    CaCN2                    45 <325 M                             P    0.20                                      600.22-0.28% Si    J680*       50    CaCN2                    50 <325 M                             P    0.20                                      601.40-1.50% Mn   J674       65    CaSi   35 8 M × D                             B    0.20                                      80   J675       60    CaC2                    40 16 M × D                             P    0.20                                      85   J676       65    CaC2                    35 16 M × D                             P    0.20                                      85   J673       60    CaSi   40 8 M × D                             B    0.20                                      85Carbon Steels:   J634       60    CaSi   40 8 M × D                             P    0.25                                       68** 0.080.03-0.07% Al   J699       60    CaSi   40 8 M × D                             Loose                                  0.20                                      81    0.170.27-0.33% Si   J673       60    CaSi   40 8 M × D                             B    0.20                                      85    0.131.35-1.60% Mn   J714       60    CaSi   40 8 M × D                             P    0.20                                      86    0.16   J734       60    CaSi   40 8 M × D                             BC   0.19                                      89    0.08   J747       60    CaSi   40 8 M × D                             BC   0.21                                      90    0.10Semi-Killed:   J709       60    CaSi   40 8 M × D                             P     0.149                                      75    0.300.07-0.12% Si   J708       60    CaSi   40 8 M × D                             P    0.15                                      75    0.210.62-0.71% Mn   J707       60    CaSi   40 8 M × D                             P    0.16                                      79    0.16   J702       60    CaSi   40 8 M × D                             BC   0.15                                      89    0.38   J735       60    CaSi   40 70 M × D                             BC   0.20                                      90    0.08   J700       60    CaSi   40 8 M × D                             BC   0.16                                      93    0.10   J701       60    CaSi   40 8 M × D                             BC   0.16                                      93    0.25Plain Carbon:   J710       60    CaSi   40 8 M × D                             P    0.15                                      75    0.100.19-0.29% Si   J711       60    CaSi   40 8 M × D                             P    0.17                                      85    0.200.54-0.85% Mn   J713       60    CaSi   40 8 M × D                             BC   0.17                                      86    0.38   J706       60    CaSi   40 8 M × D                             BC   0.15                                      88    0.40   J705       60    CaSi   40 8 M × D                             BC   0.15                                      88    0.31   J703       60    CaSi   40 8 M × D                             BC   0.15                                      90    0.11   J712       60    CaSi   40 8 M × D                             P    0.18                                      92    0.29   J704       60    CaSi   40 8 M × D                             BC   0.16                                      92    0.18__________________________________________________________________________ .sup.(1) Vanadium Source: V2 O3  >99% pure, 100 M × 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). CaN2  >99% pure, 325 M × D (chemical reagent). CaC2  Foundry grade, 66.5% CaC2 (commercial product UCC)  (1/4" × 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 V2 O.sub. + CaCN2 was plunged. **Presumed erratic result

                                  TABLE II__________________________________________________________________________Effect of Packing Density and Steel Compositions on Vanadium RecoveriesVanadium Source: 60% V2 O3 + 40% CaSi (8 M × D)         Composition of Furnace% Y      Addition         "3 Minute" Pintube (Steel)                             % VHeat No.Added    Method*         % C % Si                 % Al                     % Mn                         % V Recovery__________________________________________________________________________ **J634J620J673J714 0.250.130.200.20     PPBP          0.0770.0850.1300.16              0.240.300.230.275                  0.0570.0590.0740.061                      1.491.511.511.514                          0.160.1140.170.172                              68888586                                    ##STR2##                                      Al-KilledincreasingC content  J699J655J656 0.200.200.20     No PPP          0.170.210.22              0.2840.290.32                  0.0630.0550.05                      1.6091.641.69                          0.1610.1800.17                              819087                                    ##STR3##  JZ734J747 0.1860.2052     BCBC           0.080.10              0.160.39                  ##STR4##                      0.500.82                          0.1650.19                              8993                                    ##STR5##                                      Semi-KilledincreasingC                                     content  J700J707 0.1720.20     ##STR6##          0.180.16              0.0690.107                  ##STR7##                      0.6570.704                          0.160.158                              ##STR8##                                    ##STR9##  J701J708 0.1720.20     ##STR10##          0.250.21              0.0690.106                  ##STR11##                      0.640.704                          0.160.15                              ##STR12##                                    ##STR13##  J702J709 0.1720.20     ##STR14##          0.380.30              0.0670.121                  No AlAdded                      0.7080.626                          0.1530.149                              ##STR15##                                    ##STR16##  J703J710 0.1720.20     ##STR17##          0.110.10              0.210.245                  ##STR18##                      0.5430.573                          0.1540.15                              ##STR19##                                    ##STR20##                                      Plain Cincreasing  J704J711 0.1720.20     ##STR21##          0.180.20              0.1950.287                  ##STR22##                      0.5430.616                          0.1590.17                              ##STR23##                                    ##STR24##  J705J712 0.1720.20     ##STR25##          0.310.29              0.2330.253                  ##STR26##                      0.8730.861                          0.1520.183                              ##STR27##                                    ##STR28##                                     Plain CincreasingC content  J706J713 0.1720.20     ##STR29##          0.400.38              0.2240.252                  ##STR30##                      0.8310.845                          0.1520.172                              ##STR31##                                    ##STR32##__________________________________________________________________________ *The vanadium additions were made by plunging steel foil envelopes containing the 60% V2 O3 + 40% calciumsilicon mixtures into molten steel (1660° C. ± 5° C.). The mixtures were place in 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.                     V2 O3                         % Size   Method*                                       Added                                           Recovered__________________________________________________________________________Low Carbon:   0.036-0.05% Al, 0.10-0.12% C,                  J798                     60  40                           150 M × 0                                  B    0.25                                           92   0.16-0.31% Si, 1.50-1.60% Mn                  J799                     60  40                           100 M × 0                                  B    0.25                                           96                  J800                     60  40                           8 M × 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                           8 M × 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                           8 M × D                                  P    0.20                                           87                  J655                     60  40                           8 M × D                                       0.20                                           90Semi-Killed:   0.19-0.40% Si, J735                     60  40                           70 M × D                                  BC    0.195                                           90   0.60-0.80% Mn, 0.08-0.10% C                  J747                     60  40                           70 M × D                                  BC    0.205                                           93__________________________________________________________________________ ##STR33##

              TABLE IV______________________________________Particle Size Distribution ofCalcium-Silicon Alloy (8 Mesh × Down)______________________________________       6 Mesh - Maximum        4% on  8 M       33% on  12 M       55% on  20 M       68% on  32 M       78% on  48 M       85% on  65 M       89% on 100 M       93% on 150 M       95% on 200 M______________________________________ Products of Union Carbide Corporation, Metals Division

                                  TABLE V__________________________________________________________________________Vanadium Additives for Steel Containing Carbons or Carbon Plus Nitrogen           Reducing Agent.sup.(2)                        V        % V       N   Heat       %          Particle                        Addition                             % V Recovered                                       % C (ppm)Carbon Steel:   No. V2 O3.sup.(1)           Identity                % Size  Method.sup.(3)                             Added                                 Furnace                                       Inc..sup.(4)                                           Inc..sup.(4)__________________________________________________________________________0.03-0.7% Al   J672       65  CaC2                35                  1/4" × 1/2"                        P    0.20                                 76    0.020.23-0.29% C   J671       55  CaC2                45                  1/4" × 1/2"                        P    0.20                                 77    0.030.27-0.33% Si   J657       60  CaC2                40                  1/2" × 1/4"                        P    0.20                                 83    0.031.35-1.60% Mn0.04-0.07% Al    J678*       60  CaCn2                40                  <200 M                        P    0.20                                 50    0.02                                           1200.15-0.20% C    J677*       65  CaCn2                35                  <200 M                        P    0.20                                 55    0.01                                           1020.22-0.28% Si    J679*       55  CaCn2                45                  <200 M                        P    0.20                                 60    0.03                                           1941.40-1.50% Mn    J680*       50  CaCN2                50                  <200 M                        P    0.20                                 60    0.03                                           225   J675       60  CaC2                40                  16 M × D                        P    0.20                                 85    0.04   J676       65  CaC2                35                  16 M × D                        P    0.20                                 85    0.04__________________________________________________________________________ .sup.(1) V2 O3 : 99% pure, 100 M × D (commercial product, UCC). .sup.(2) CaC2 : 80% CaC2, 14% CaO, 2.9% SiO2, 1.6% Al.sub. O3 (commercial product, UCC). CaCn2 : 50% Ca, 15% C, 35% N (chemically pure). .sup.(3) Mixture tightly packed in steel foil envelope and plunged into molten steel  1600° C. ± 5° C. .sup.(4) Increase in % C and ppm N in molten steel due to addition of vanadium plus CaC2 or CaCN2 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 V2 O5                                Ref-Property V2 O3                  V2 O5                                erence______________________________________Density  4.87          3.36          1Melting Point    1970° C.                  690° C.                                1Color    Black         Yellow        1Character of    Basic         Amphoteric    2OxideComposition    68% V + 32% O 56% V + 44% O (Calc.)Free Energy    -184,500 cal/mole                  -202,000 cal/mole                                3of Formation(1900° K.)Crystal  ao = 5.45 ± 3 A                  ao = 4.359 ± 5 A                                4Structure     α = 54°49' ± 8'                  b0 = 11.510 ± 8 A    Rhombohedral  co = 3.563 ± 3 A                  Orthohrombic______________________________________