US2806778A - Exothermic manganese addition agent - Google Patents

Exothermic manganese addition agent Download PDF

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US2806778A
US2806778A US429363A US42936354A US2806778A US 2806778 A US2806778 A US 2806778A US 429363 A US429363 A US 429363A US 42936354 A US42936354 A US 42936354A US 2806778 A US2806778 A US 2806778A
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manganese
exothermic
ore
silicon
mixture
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US429363A
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Crafts Walter
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Union Carbide Corp
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Union Carbide Corp
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C33/00Making ferrous alloys
    • C22C33/003Making ferrous alloys making amorphous alloys

Definitions

  • the big problem in adding manganese metal to a steel or cast iron bath is finding improved means for recovering manganese values in the melt.
  • the addition of manganese in furnace baths is already a problem, a large and uncertain amount of the alloying element being lost as a result of oxidation.
  • Ladle additions are more satisfactory, but further difliculty is encountered in adding manganese alloy because of the heat absorbed in dissolving the cold manganese addition. This absorption of heat by the manganese alloy addition reduces the temperature of the metallic bath, and the resulting temperature drop, if substantial enough, may in turn cause the segregation of important alloying ingredients. Such temperature drop will also increase skull formation.
  • the usual exothermic mix consists essentially of an oxidizing agent, a reducing agent, and one or more alloying metals.
  • a common oxidizing agent that is widely used is sodium nitrate, and the reducing agent is silicon.
  • Another object of the present invention is to provide a manganese-containing exothermic mix for a steel melt, the mix having a relatively high proportion of manganese content, and characterized by a more complete recovery of manganese than has heretofore been possible by the use of nonexothermic manganese addition agents.
  • a further object of the present invention is to provide in an exothermic mixture including silicon and sodium nitrate, an oxidizing agent for facilitating the incorporation of manganese values in a steel melt, the mixture being capable of evolving sufficient heat for effecting rapid solution of the manganese early in the tap to promote uniform distribution therein.
  • the present invention provides improved means for obviating the above defects. This is accomplished by including in the exothermic mixture a moderating agent to reduce the turbulent behavior of the exothermic reactants.
  • the exothermic reaction mixture of the present invention comprises sodium nitrate as oxidant, silicon as reducing agent, one or more manganese alloy additions, and as a moderator, iron ore and manganese ore.
  • silicon and the manganese content are present in the subject mixture as constituents of an alloy, for example, silico-manganese.
  • the iron ore and manganese ore present in the subject mixture serve not only to reduce the turbulence of the exothermic reaction, but also serve in the capacity of oxidants for exothermic reaction with part of the silicon present in the mixture.
  • some of the main exothermic reactions which account in large measure for the reduction in chill during the alloying operation:
  • the above formulas are based upon the use of stoichiometric proportions of sodium nitrate, iron ore and manganese ore as oxidants, and, as reducing agent, silicon.
  • the reducing agent is present in sufficient quantity to substantially reduce the sodium nitrate and the oxidic ores of iron and manganese in the mix.
  • the oxides of manganese, iron and sodium, formed as a result of the above reactions, are believed to form complex compounds or solutions in the by-product silicabearing slag formed during the reaction.
  • Combining the iron ore and manganese ore into the reaction mixture serves to utilize the accelerating effect of the iron ore for fast solution rate of the manganese addition and the excellent manganese recovery feature of the manganese ore.
  • composition range of the reaction mixture embodying the principles of the present invention may be varied over a considerable range without impairing its exothermic prop erties. Best results are obtained when the percentages of the constituents of the instant exothermic mixture lie within the composition range listed below in Table II. The analysis of the constituents in Table II is typical.
  • sodium nitrate is admixed with suificient amounts of silicomangane-se alloy, iron ore and manganese ore to produce an exothermic alloy addition agent containing at least 45% available manganese.
  • the ingredients of the mixture are preferably of mesh size (i. e., capable of passing through a screen having 0.147 mm. openings), with the exception of the sodium nitrate which is of 48 mesh size (0.295 mm. openings).
  • the mix of the invention may then be applied to the melt in either bonded or unbonded form.
  • the addition agent is added in the form of pellets made by compacting the powdered mixture at approximately 2000 p. s. i. A slight amount of water may be added.
  • An addition agent for a ferrous melt comprising 9.0% to 20.0% manganese ore, 2.0% to 9.0% iron ore, 10% to 20% sodium nitrate, remainder silicomanganese alloy, and characterized by fast solution rate, relatively high manganese recovery and relatively high exo thermicity.
  • An addition agent for ferrous melt comprising 12% to 20% iron ore and manganese ore, the proportion of said manganese ore to said iron ore being between 2.5 to 1.0 and 6.0 to 1.0, 10% to 20% sodium nitrate, remainder silicomanganese, and characterized by relatively high manganese recovery in the melt, fast solution rate and relatively high exothermicity.
  • An addition agent for a ferrous melt comprising 9.0% to 20% oxidic manganese ore, 2.0% to 9.0% oxidic iron ore, 10% to 20% sodium nitrate, remainder silicomanganese alloy, the proportion of said manganese ore to said iron ore being between 2.5 to 1.0 and 6.0 to 1.0.

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

Description

United States Patent Walter Crafts, Niagara Carbide (Iorporation,
No Drawing. Application May 12, 1954, Serial No. 429,363
3 Claims. (Cl. 75-27) Falls, N. Y., assignor to Union a corporation of New York This invention relates to improved exothermic reaction mixtures, and more particularly concerns exothermic manganese addition agents for a ferrous melt.
The big problem in adding manganese metal to a steel or cast iron bath is finding improved means for recovering manganese values in the melt. The addition of manganese in furnace baths is already a problem, a large and uncertain amount of the alloying element being lost as a result of oxidation. Ladle additions are more satisfactory, but further difliculty is encountered in adding manganese alloy because of the heat absorbed in dissolving the cold manganese addition. This absorption of heat by the manganese alloy addition reduces the temperature of the metallic bath, and the resulting temperature drop, if substantial enough, may in turn cause the segregation of important alloying ingredients. Such temperature drop will also increase skull formation.
It has been known for some time that the temperature drop that accompanies the addition of alloying elements to a steel melt may be reduced to an appreciable extent by the addition of reaction materials having exothermic properties. In the production of steel alloys using such materials, the usual practice is to add an exothermic mixture including the alloying materials to a steel or cast iron melt, and to so proportion the constituents of the exothermic mix that the heat generated is sufficient to substantially reduce the amount of chill that would otherwise result from such alloy addition. The usual exothermic mix consists essentially of an oxidizing agent, a reducing agent, and one or more alloying metals. A common oxidizing agent that is widely used is sodium nitrate, and the reducing agent is silicon.
One of the difiiculties inherent in a reaction mixture containing sodium nitrate as oxidizing agent, silicon as reducing agent, and an addition of manganese alloy is the violence of the exothermic reaction. The explosive nature of the exothermic reaction causes part of the manganese alloy content to be hurled outside the ladle and, as a consequence, reduces considerably the recovery of available manganese. And too, the heat of the reaction is dissipated to the atmosphere rather than transferred to the metal.
In order to improve the recovery of manganese values in a silicon-sodium nitrate exothermic mixture, control over the exothermic reaction is essential. To eifect this control, the violence of the exothermic reaction must be reduced. At the same time, the stabilization of the exothermic reaction must not proceed so far as to jeopardize the fulfillment of the exothermic function by either chilling the molten bath or decreasing the rate of dissolution of the manganese alloying addition.
It is, therefore, an important object of the present invention to introduce manganese additions to molten steel in the form of an exothermic mixture containing silicon and sodium nitrate to overcome the objectionable effects isted above, without reducing to any significant degree the rate of solution of the manganese addition, thereby elfecting maximum recovery of the manganese available in the exothermic mixture.
Another object of the present invention is to provide a manganese-containing exothermic mix for a steel melt, the mix having a relatively high proportion of manganese content, and characterized by a more complete recovery of manganese than has heretofore been possible by the use of nonexothermic manganese addition agents.
A further object of the present invention is to provide in an exothermic mixture including silicon and sodium nitrate, an oxidizing agent for facilitating the incorporation of manganese values in a steel melt, the mixture being capable of evolving sufficient heat for effecting rapid solution of the manganese early in the tap to promote uniform distribution therein.
In manganese addition agents containing silicon and sodium nitrate as exothermic reactants, the violence with which heat is released is undesirable, particularly in steel operations. The low recovery of available manganese in the exothermic mixture due to the turbulence of the exothermic reaction, and the hazardous conditions created thereby, are but some of the conditions that require remedial action. The present invention provides improved means for obviating the above defects. This is accomplished by including in the exothermic mixture a moderating agent to reduce the turbulent behavior of the exothermic reactants.
It has been found that the undesirably violent eruptions that take place upon the ignition of a reaction mixture of the silicon-sodium nitrate type in a steel bath may be substantially eliminated by introducing into the reaction mixture a moderating agent consisting of oxidic ores of iron and manganese, for example FezOs and M1102. Yet sufficiently rapid rates of reaction and of assimilation of the available manganese in the addition agent are maintained, and temperature drop due to the addition of the mixture is not excessive.
Accordingly, the exothermic reaction mixture of the present invention comprises sodium nitrate as oxidant, silicon as reducing agent, one or more manganese alloy additions, and as a moderator, iron ore and manganese ore. Preferably the silicon and the manganese content are present in the subject mixture as constituents of an alloy, for example, silico-manganese.
According to the present invention, the iron ore and manganese ore present in the subject mixture serve not only to reduce the turbulence of the exothermic reaction, but also serve in the capacity of oxidants for exothermic reaction with part of the silicon present in the mixture. Following are some of the main exothermic reactions which account in large measure for the reduction in chill during the alloying operation:
Other side reactions which also occur during ignition of the reaction mix, and which contribute to the exothermicity thereof are:
The above formulas are based upon the use of stoichiometric proportions of sodium nitrate, iron ore and manganese ore as oxidants, and, as reducing agent, silicon. Thereby, the reducing agent is present in sufficient quantity to substantially reduce the sodium nitrate and the oxidic ores of iron and manganese in the mix.
The oxides of manganese, iron and sodium, formed as a result of the above reactions, are believed to form complex compounds or solutions in the by-product silicabearing slag formed during the reaction.
In order that the invention may be more fully appreciat it may be noted at this point that exothermic reaction mixtures containing silicon, sodium nitrate and manganese behave dilferently when either iron ore or manganese ore is employed as the oxidic moderating agent. For instance, individual experiments show that while iron is successful in inhibiting the activity of the exothermic mixture, it is not altogether satisfactory from a standpoint of efliciency since much of the silicon is recovered in the steel melt. This might be due to only partial reaction of the iron ore with the silicon and reaction with the manganese as well since part of the manganese is oxidized and lost as slag, thereby depriving the steel of its intended alloying ingredient. n the other hand, manganese ore alone acts to improve beneficially the manganese recovery, with little or no silicon absorbed by the steel. However, the solution time of the manganese addition in the steel melt is lengthened.
Combining the iron ore and manganese ore into the reaction mixture serves to utilize the accelerating effect of the iron ore for fast solution rate of the manganese addition and the excellent manganese recovery feature of the manganese ore.
In order to indicate still more fully the nature of the present invention, results of tests showing the effects of manganese ore and iron ore, either individually or in combination with each other, in manganese addition agents containing silicomanganese and sodium nitrate are tabulated below in Table I, it being understood that these tests are presented as illustrative only, and that they are not intended to limit the scope of the invention. The data reported in Table I are the results of a series of tests in which a suflicient quantity of manganese addition agent was added to a 100 pound bath of molten steel to raise the manganese content of the steel 1%, the bath being at a temperature of about 1600 C.
Table I Temper- Percent Percent Composition of Exonture Solution Indicated Indicated thermic Addition Agent Drop Time, Mon Silicon 0. seconds ganese Recovery Recovery 68.5% SiMn, 9% N eNOa, 22%
Mn ore 7 55 100 28 68.5% SiMn, 14% NaNO 17% Fe Ore, 0.5% Mogul Binder .t 7 74 47 68.5% SlMn, 14% NBNOs,
17% Mn ore 6 50 100 28 68.5% SlMn, 14% NaN 0;,
15% Mn ore, 2.5% Fe ore... 5 45 89 9 68.5% SlMn, 14% N aN 0:,
12.5% Mn ore, 5% Fe ore. 6 91 nil 68.5% SiMn, 17% NaN 0:,
9.5% Mn ore, 5% Fe ore 0 33 83 9 68.5% SlMn, 19% NaN0;,
12% Mn ore B 60 104 nil The above table demonstrates that the employment of iron ore alone in exothermic mixes containing silicon and sodium nitrate results in relatively good solution time (25 seconds), relatively poor manganese recovery (74% and relatively high silicon recovery (47%). With only manganese ore in the mixture, manganese recovery is at a maximum (100%), silicon recovery fair (28%), and solution time, about one minute. Tests employing both manganese ore and iron ore exhibited relatively high indicated manganese recoveries amounting to 83% or better and solution times of 45 seconds or less. Silicon recoveries in the melt amounted to less than 10%, and in some instances were present only as traces.
It will be noted from the above table that the composition range of the reaction mixture embodying the principles of the present invention may be varied over a considerable range without impairing its exothermic prop erties. Best results are obtained when the percentages of the constituents of the instant exothermic mixture lie within the composition range listed below in Table II. The analysis of the constituents in Table II is typical.
Table II M nximum Preferred Optimum results are obtained when the ratio of manganese ore to iron ore is between 2.5 to 1.0 and 6.0 to 1.0.
In practicing the invention, sodium nitrate is admixed with suificient amounts of silicomangane-se alloy, iron ore and manganese ore to produce an exothermic alloy addition agent containing at least 45% available manganese. The ingredients of the mixture are preferably of mesh size (i. e., capable of passing through a screen having 0.147 mm. openings), with the exception of the sodium nitrate which is of 48 mesh size (0.295 mm. openings). The mix of the invention may then be applied to the melt in either bonded or unbonded form. In the present instance, the addition agent is added in the form of pellets made by compacting the powdered mixture at approximately 2000 p. s. i. A slight amount of water may be added.
Incorporation of the mixture into the steel melt in an amount equivalent to 1% Mn results in average temperature drop of less than 8 C., an average solution time of less than 45 seconds, and negligible silicon recoveries. Manganese recoveries, amounting to as high as 91% confirm the acceptability of the instant mix. Tests show that the available manganese recovered in the melt is distributed uniformly throughout the melt.
It will be understood that modifications and variations may be effected without departing from the novel concepts of the present invention.
What is claimed is:
1. An addition agent for a ferrous melt comprising 9.0% to 20.0% manganese ore, 2.0% to 9.0% iron ore, 10% to 20% sodium nitrate, remainder silicomanganese alloy, and characterized by fast solution rate, relatively high manganese recovery and relatively high exo thermicity.
2. An addition agent for ferrous melt comprising 12% to 20% iron ore and manganese ore, the proportion of said manganese ore to said iron ore being between 2.5 to 1.0 and 6.0 to 1.0, 10% to 20% sodium nitrate, remainder silicomanganese, and characterized by relatively high manganese recovery in the melt, fast solution rate and relatively high exothermicity.
3. An addition agent for a ferrous melt comprising 9.0% to 20% oxidic manganese ore, 2.0% to 9.0% oxidic iron ore, 10% to 20% sodium nitrate, remainder silicomanganese alloy, the proportion of said manganese ore to said iron ore being between 2.5 to 1.0 and 6.0 to 1.0.
References Cited in the file of this patent UNITED STATES PATENTS 1,431,621 Benekcr Oct. 10, 1922 1,623,757 Saklatwalla Apr. 5, 1927 1,820,998 Becket Sept. 1, 1931 2,243,784 Udy May 27, 1941 2,367,630 Udy Jan. 16, 1945

Claims (1)

1. AN ADDITION AGENT FOR A FERROUS MELT COMPRISING 9.0% TO 20.0% MANGANESE ORE, 2.0% TO 9.0% IRON ORE, 10% TO 20% SODIUM NITRATE, REMAINDER SLICOMANGANESE ALLOY, AND CHARACTERIZED BY FAST SOLUTION RATE, RELATIVELY HIGH MAGANESE RECOVERY AND RELATIVELY HIGH EXOTHERMIICITY.
US429363A 1954-05-12 1954-05-12 Exothermic manganese addition agent Expired - Lifetime US2806778A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50128614A (en) * 1974-03-29 1975-10-09
US20110094336A1 (en) * 2007-12-14 2011-04-28 Salzgitter Flachstahl Gmbh Method for producing a steel melt containing up to 30% manganese

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1431621A (en) * 1921-03-01 1922-10-10 Frederick F Mcintosh Method of manufacturing steel
US1623757A (en) * 1926-06-05 1927-04-05 Byramji D Saklatwalla Manufacture of chromium-iron alloys
US1820998A (en) * 1928-04-13 1931-09-01 Electro Metallurg Co Smelting of ores
US2243784A (en) * 1939-10-26 1941-05-27 Marvin J Udy Method and material suitable for use in the production of molten metal products
US2367630A (en) * 1942-07-09 1945-01-16 Marvin J Udy Metallurgy

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1431621A (en) * 1921-03-01 1922-10-10 Frederick F Mcintosh Method of manufacturing steel
US1623757A (en) * 1926-06-05 1927-04-05 Byramji D Saklatwalla Manufacture of chromium-iron alloys
US1820998A (en) * 1928-04-13 1931-09-01 Electro Metallurg Co Smelting of ores
US2243784A (en) * 1939-10-26 1941-05-27 Marvin J Udy Method and material suitable for use in the production of molten metal products
US2367630A (en) * 1942-07-09 1945-01-16 Marvin J Udy Metallurgy

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50128614A (en) * 1974-03-29 1975-10-09
JPS545764B2 (en) * 1974-03-29 1979-03-20
US20110094336A1 (en) * 2007-12-14 2011-04-28 Salzgitter Flachstahl Gmbh Method for producing a steel melt containing up to 30% manganese
US8444743B2 (en) * 2007-12-14 2013-05-21 Salzgitter Flachstahl Gmbh Method for producing a steel melt containing up to 30% manganese

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