US3681051A - Desulfurizing agent for molten pig iron - Google Patents

Desulfurizing agent for molten pig iron Download PDF

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Publication number
US3681051A
US3681051A US881953A US3681051DA US3681051A US 3681051 A US3681051 A US 3681051A US 881953 A US881953 A US 881953A US 3681051D A US3681051D A US 3681051DA US 3681051 A US3681051 A US 3681051A
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US
United States
Prior art keywords
weight
pig iron
molten pig
desulfurizing
desulfurizing agent
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US881953A
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English (en)
Inventor
Masaru Takashima
Masao Saito
Shigeru Matsuyama
Kazufusa Ueki
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Aikoh Co Ltd
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Aikoh Co Ltd
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Publication of US3681051A publication Critical patent/US3681051A/en
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12222—Shaped configuration for melting [e.g., package, etc.]

Definitions

  • the present invention relates to an agent for desulfurizing molten pig iron.
  • a desulfurizing agent consisting of an alkali or alkaline earth metal compound into the ladle or mixer or receiver, and to allow the charge to stand or to agitate the molten metal by means of an external force so as to effect a reaction between the molten metal and the agent for desulfurization.
  • a shaking ladle is used or an inert gas is blown in.
  • the present invention aims at improvements in a desulfurizing agent of particular formulation and shapes adapted to increase the usual desulfurizing rate without resorting to any of the complicate procedures and with no possibility of loss by scattering of the agent itself as above described, and also of an agent which is easy to operate for the desulfurization of molten pig iron outside the furnace.
  • the desulfurizing agent to be molded into blocks of many different shapes is composed essentially of soda ash (anhydrous sodium carbonate) and portland cement, containing, where necessary, much smaller proportions of water glass, borax, sodium chloride, a calcium-containing substance such as calcium oxide, calcium carbonate, calcium hydroxide, calcium fluoride, or calcium chloride, a carbonaceous substance such as coke dust, graphite powder, or charcoal powder, and iron powder.
  • composition and shape of the desulfurizing agent for molten pig iron according to the present invention are such that the agent consists of 60 to by weight, preferably 70 to 83% by weight, of soda ash (anhydrous sodium carbonate) and '3 to 25 by weight of portland cement, mixed, according to the necessity, with 0 to 10% by weight of water glass, 0 to 5% by weight of borax, 0 to 5% by weight of sodium chloride, 0 to 10% by Weight of calcium-containing substance, 0 to 5% by weight of carbonaceous substance, 0 to 10% by weight of iron powder, and contains 7 to 15% by weight of water, and the homogeneous composition thus obtained which has an apparent specific gravity of 1.3 to 2.5 is molded to a block or the like having one or more holes or grooves formed therethrough.
  • FIGS. 1 to 7 are perspective views of a desulfurizing agent molded to different forms in accordance with the present invention.
  • FIGS. 8 to 10 are perspective views of fragmentary parts of an expanded metal and perforated iron sheets to be used in the process of the invention.
  • FIG. 11 is a perspective view of an assembly of molded blocks of the desulfurizing agent supported by an iron framed base and covered on top with a punched iron sheet to a unitary construction;
  • FIG. 12 is a vertical sectional view showing the lower part of a ladle for molten pig iron that contains a unitary assembly as illustrated in FIG. 11;
  • FIG. 13 is a perspective view of a cubic assembly of molded pieces of a desulfurizing agent bound together as if crated with flat steel bands;
  • FIG. 14 is a perspective view of an exemplary molded block of a desulfurizing agent which is formed with a multiplicity of through holes.
  • FIGS. 1 to 7 illustrate some examples of shapes in which the moldings may take.
  • the moldings may be either blocks such as shown in FIGS. 1 and 2 which are substantially cubic with fiat horizontal surfaces 1 on top and bottom for the facility of assembling and formed with a hole 2 therethrough or blocks being L, U, W or likewise shaped in section and provided with one or more vertical grooves 2 or recesses as shown in FIGS. 3 to 7. In either case, they are so shaped as to facilitate heaping one upon another combining altogether in block assembly while forming one or more vertical holes or bores through the entire assembly.
  • the desulfurizing blocks according to the invention are placed side by side and one upon another or assembled together on a base equipped with corner posts of iron in such a manner that the holes or grooves formed through the individual blocks can communicate with one another to form vertical holes hrough the entire asembly, and then an expanded metal 3 having a lattice of spaces 4 as shown in FIG. 8 or a sheet iron 3 punched with holes 4 as in FIG. 9 or 10, or a sheet iron or the like is fitted as a cover onto the top of the assembly to a unitary construction.
  • FIG. 11 is a perspective view of an assembly of the desulfurizing blocks 1 which are placed side by side and one upon another over the base members 5 and 6 provided with corner posts of iron and covered with a punched sheet iron 3 on the top to an integral unit.
  • the holes 4 formed through the sheet iron are substantially aligned to the individual holes or grooves through the deforming blocks.
  • FIG. 12 is a vertical sectional view of a unitary assembly of a certain number of desulfurizing blocks according to the invention as placed in a vessel 7 for containing molten pig iron.
  • the holes 4 formed through the sheet iron 3 correspond to the through holes or grooves 2 of the individual desulfurizing blocks 1 in vertical communication therewith.
  • FIG. 13 shows an assembly of desulfurizing blocks 1 of the invention as assembled on a base 5 equipped with corner frames of iron and bound together with fiat steel bands 8 or the like.
  • the present invention is the composition and configurations of an agent for eliminating sulfur from molten pig iron easily and efliciently without recourse to mechanical power, and the mechanism of the desulfurizing reaction involved.
  • Soda ash the essential component of the desulfurizing agent according to the invention, is most responsible for the desulfurizing action. It can be preferably used the soda ash having the following purity:
  • Portland cement another component of the agent, avoids resulfurization because CaO which constitutes a preponderance of the cement composition undergoes a subsitution reaction with Na s that is produced by the reaction Formula 1 above and thereby forms more stable CaS. It also serves as a binder.
  • the desulfurizing agent of the invention has the composition and configuration as described hereinabove, it should be noted, in particular, that the agent is shaped to polygonal cubes or blocks with large areas to contact molten pig iron so that, when floated on the molten metal, the blocks are always immersed partly but deep into the melt, unlike conventional desulfurizing agents of other forms.
  • the size of the molded blocks is increased in proportion to the volume of the melt to be desulfurized. A usually preferable range of the size is between 3 and 500 mm, for each side.
  • the present invention is illustrated by the following examples, in which the use of the desulfurizing agent and process according to the present invention are compared with the use of soda ash powder and moldings.
  • composition of the desulfurizing agent according to the present invention are shown in the following table.
  • soda ash is principally responsible for the desulfurizing action .of the agent according to the invention, it is desired to account for as large percent as possible of the composition. However, the percent by weight is limited to 60 to 85 by the necessity of presence of other effective ingredients.
  • Portland cement not only avoids resulfurization because its major constituent CaO reacts for substitution with sulfide of soda that is produced by the reaction Formula 1 and thereby forms stable Na S, but also serves as a binder. To attain these ends, it is suitably used in the range of 3 to 25% by weight of the total amount of the desul furizing composition. When used in an amount of less than 3%, the cement is unable to act as a binder and fails to maintain the strength of the moldings. With an increase in the amount, its adds accordingly to the strength of the resulting moldings, but it should not be employed in excess of 25% because it brings too much calcium and silicate into the composition for ready melting of the agent and it thus reduces the desulfurizing effect of the agent.
  • Water glass is used as a quick hardening agent that promotes the setting of portland cement. It is added in an amount of not more than 10% by Weight to a desulfurizing composition for introduction into a large molten pig iron ladle. Any amount exceeding 10% is not desirable since the silicate content is increased to such an extent that it hinders the melting of the desulfurizing agent. Where the desulfurizing agent is to be introduced into a receiver or small ladle for molten pig iron, the use of water glass is not necessary.
  • Borax and sodium chloride are sometimes required for the adjustment of slag viscosity. In such case they are employed in the range of 0 to 5% by Weight each. Usually they need not be used in amounts of more than 5%.
  • a calcium-containing substance such as calcium oxide, calcium carbonate, calcium hydroxide, calcium fluoride, or calcium chloride is used in an amount of not more than 10% by weight in order to avoid resulfurization as it forms stable calcium sulfide through a substitution reaction with sulfide of soda that is obtained by the reaction Formula 1. Any amount exceeding 10% is objectionable because it hampers melting of the desulfurizing agent.
  • a carbonaceous substance such as coke, graphite, or charcoal is used to raise the temperature of molten pig iron when it is at a realtively low temperature and also to make up for the loss due to combustion of carbon in the molten pig iron during the course of the desulfurization reaction with soda ash and calcium oxide.
  • melt temperature is too low, the further drop of the temperature due to the endothermic reaction with the desulfurizing agent may render subsequent operation impossible.
  • this may lead to consumption of the carbon content during the desulfurization beyond the allowable limit, thus making it necessary to add carbon and heat the molten pig iron.
  • carbonaceous substance is used in an amount of not more than 5% by weight. Any excess of the amount simply burns on the surface of the molten metal and the effect that is achieved is, in essence, little different from the eifect with 5% only. Rather, it merely reduces the relative proportions of the other efiective ingredients of the desulfurizing agent.
  • Iron powder is incorporated with the view to increasing the apparent specific gravity of the desulfurizing agent.
  • the apparent specific gravity of the desulfurizing blocks is increased sufliciently to permit the blocks to sink below the surface slag layer and in contact with the molten metal. It therefore should be obvious that the desulfurizing blocks have the greatest apparent specific gravity possible. If the desulfurizing blocks are to sink under the slag layer without difliculty, they should have an apparent specific gravity of at least 1.3.
  • composition When the composition is molded without inclusion of iron powder, it can have an apparent specific gravity of up to 1.8. But when an even higher value is desired, inclusion of some heavy substance is necessary. In the sense that it does not aifect the properties of the particular molten pig iron, iron powder of the same kind is most preferred for such purpose.
  • the apparent specific gravity of the desulfurizing agent can be varied over a range of 1.8 to 2.5. Any amount exceeding 10% is not desirable in that the contents of other effective ingredients of the desulfurizing agent must be decreased accordingly, though the apparent specific gravity of the agent as a Whole can be increased. With an apparent specific gravity of up to 2.5, the purpose of sinking the desulfurizing blocks below the slag layer can be fully achieved.
  • the water content of the desulfurizing blocks is suitably between 7 and 15% by weight.
  • a water content of less than 7% makes the blocks readily collapsible and difficult to handle, while blocks containing more than 15% water are not desirable because of the too violent reaction with molten pig iron that comes into contact.
  • the shapes of the desulfurizing blocks according to the present invention are such as shown in FIGS. 1 to 7, having one or more through holes or grooves which extend straightly from one side to the other.
  • the blocks have polygonal and cubic shapes so that they have large areas in contact with molten pig iron and are partly immersed deep into the melt as they float thereon.
  • the individual blocks Preferably have large sizes when to be used with large volumes of molten pig iron; they should measure not smaller than 30 mm. for each side.
  • Procedures for desulfurizing molten pig iron in large-capacity ladles consisting in the use of a desulfurizing agent according to the present invention, either in the form of a unitary assembly of a predetermined quantity of the blocks as shown in FIG. 11 or FIG. 15 or in the form of a single block as shown in FIG. 14 which is large enough to accomplish the desulfurization of molten pig iron in the particular vessel, and which is preset in the ladle as shown in FIG. 12, and subsequent pouring of molten pig iron into the ladle for desult-urization.
  • the molded blocks of the desulfurizing agent are placed side by side and one upon another or assembled together in such a way that their respective through holes or grooves run up and down in communication with ane another, thereby forming a multiplicity of substantially vertical holes which extend from the top end to the bottom of the assembly.
  • the melt flows down through the holes of the desulfurizing blocks and reaches the bottom of the vessel, with the consequence that the desulfurizing blocks as a whole float up 6 and the molten pig iron continuously poured in therethrough takes the same course and is thereby freed from sulfur.
  • the dimensions of the molded blocks of the desulfurizing agent are so adjusted that the time during which the desulfurizing agent collapses in contact with molten pig iron substantially corresponds to the pouring time. Since all the molten pig iron poured into the ladle flows down through the surface of the desulfurizing blocks, a perfect contact is ensured between the molten pig iron and the desulfurizing agent without the application of any external force. With no such disadvantage of non-homogeneity due to agitation with external force of a large amount of molten metal in a large ladle, the pouring time is directly taken advantage of in accomplishing the desulfurization within a short period of time to a great practical advantage.
  • the present invention is further characterized by the use of portland cement which can produce stable CaS as a component of a desulfurizing agent for molten pig iron and also as a binder.
  • portland cement which can produce stable CaS as a component of a desulfurizing agent for molten pig iron and also as a binder.
  • it provides molded shapes of desulfurizing agent having certain formulations and configurations and permits des-ulfurization of molten pig iron extremely effectively with the use of a desulfurizing agent of certain shapes in certain ways.
  • the desulfurizing agent and process according to the present invention are far more advanced and industrially advantageous over the conventional ones.
  • a homogeneous molded desulfurizing agent for molten pig iron having a specific gravity of between 1.3 and 2.5 and being a homogeneous composition consisting only of: to 85% by weight of soda ash, 3 to 25% by weight of portland cement, 0 to 10% by weight of water glass, 0 to 5% by weight of borax, 0 to 5% by weight of sodium chloride, 0 to 10% by weight of a calcium-containing substance, 0 to 5% by weight of a carbonaceous substance, 0 to 10% by weight of iron powder, and 7 to 15% by weight of water.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Processing Of Solid Wastes (AREA)
  • Mold Materials And Core Materials (AREA)
US881953A 1969-08-13 1969-12-04 Desulfurizing agent for molten pig iron Expired - Lifetime US3681051A (en)

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JP44063572A JPS4827568B1 (cs) 1969-08-13 1969-08-13

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US (1) US3681051A (cs)
JP (1) JPS4827568B1 (cs)
AT (1) AT318670B (cs)
BE (1) BE742834A (cs)
ES (1) ES374601A1 (cs)
FR (1) FR2077499A1 (cs)
GB (1) GB1290495A (cs)
SE (1) SE362264B (cs)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2252795A1 (de) * 1972-10-27 1974-05-22 Sueddeutsche Kalkstickstoff Entschwefelungsmittel fuer metallschmelzen mit wasserabspaltendem zusatz
US3865577A (en) * 1971-12-20 1975-02-11 Metallurg Forschungsanstalt Body for deoxidizing molten steel by submersion therein
US3871869A (en) * 1972-02-10 1975-03-18 Hoogovens Ijmuiden Bv Process for pressing briquettes from powdered substances more particularly from fine-grained fluorspar and briquettes thus obtained
US3934862A (en) * 1973-04-12 1976-01-27 Labate Michael D Device for supplying a treating agent to molten metal in a ladle
US3957502A (en) * 1971-11-17 1976-05-18 Magnesium Elektron Limited Addition of magnesium to molten metal
US4127407A (en) * 1976-04-07 1978-11-28 Eitel Hans J Method of making a casting powder
US4199353A (en) * 1977-01-18 1980-04-22 Canron Inc. Molten metal treatment
US4208207A (en) * 1975-10-15 1980-06-17 Tareh El Gammal Carrier body and method for introduction of a reaction agent into metal melts
US4233064A (en) * 1978-09-13 1980-11-11 Dunn Jr Edward J Method of scavenging steel
US4306904A (en) * 1977-10-11 1981-12-22 Societe Francaise D'electrometallurgie Sofrem Process of introducing a solid addition into a bath of liquid metal
US4310147A (en) * 1979-08-13 1982-01-12 Widmer Colin F Cooled components for furnaces
US4451293A (en) * 1979-05-31 1984-05-29 Quiqley Company, Inc. Slag-forming agent and process for producing the agent
US4729548A (en) * 1986-09-04 1988-03-08 Richland Industrial, Inc. Refractory coating for metal
US4783057A (en) * 1986-09-04 1988-11-08 Richland Industrial, Inc. Of Columbia, Sc Metal refining with refractory coated pipe
WO1989006706A1 (en) * 1986-09-04 1989-07-27 Richland Industrial, Incorporated Heat resistant composite and method of making the same
US5066350A (en) * 1982-06-09 1991-11-19 Richland Industrial, Inc. Method of applying a refractory coating to a conduit

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5048801U (cs) * 1973-09-04 1975-05-14
US4572737A (en) * 1984-06-27 1986-02-25 The Boc Group, Inc. Agents for the removal of impurities from a molten metal and a process for producing same

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3957502A (en) * 1971-11-17 1976-05-18 Magnesium Elektron Limited Addition of magnesium to molten metal
US3865577A (en) * 1971-12-20 1975-02-11 Metallurg Forschungsanstalt Body for deoxidizing molten steel by submersion therein
US3871869A (en) * 1972-02-10 1975-03-18 Hoogovens Ijmuiden Bv Process for pressing briquettes from powdered substances more particularly from fine-grained fluorspar and briquettes thus obtained
DE2252795A1 (de) * 1972-10-27 1974-05-22 Sueddeutsche Kalkstickstoff Entschwefelungsmittel fuer metallschmelzen mit wasserabspaltendem zusatz
US3934862A (en) * 1973-04-12 1976-01-27 Labate Michael D Device for supplying a treating agent to molten metal in a ladle
US4208207A (en) * 1975-10-15 1980-06-17 Tareh El Gammal Carrier body and method for introduction of a reaction agent into metal melts
US4127407A (en) * 1976-04-07 1978-11-28 Eitel Hans J Method of making a casting powder
US4199353A (en) * 1977-01-18 1980-04-22 Canron Inc. Molten metal treatment
US4306904A (en) * 1977-10-11 1981-12-22 Societe Francaise D'electrometallurgie Sofrem Process of introducing a solid addition into a bath of liquid metal
US4233064A (en) * 1978-09-13 1980-11-11 Dunn Jr Edward J Method of scavenging steel
US4451293A (en) * 1979-05-31 1984-05-29 Quiqley Company, Inc. Slag-forming agent and process for producing the agent
US4310147A (en) * 1979-08-13 1982-01-12 Widmer Colin F Cooled components for furnaces
US5066350A (en) * 1982-06-09 1991-11-19 Richland Industrial, Inc. Method of applying a refractory coating to a conduit
US4729548A (en) * 1986-09-04 1988-03-08 Richland Industrial, Inc. Refractory coating for metal
US4783057A (en) * 1986-09-04 1988-11-08 Richland Industrial, Inc. Of Columbia, Sc Metal refining with refractory coated pipe
WO1989006706A1 (en) * 1986-09-04 1989-07-27 Richland Industrial, Incorporated Heat resistant composite and method of making the same

Also Published As

Publication number Publication date
JPS4827568B1 (cs) 1973-08-23
ES374601A1 (es) 1972-01-01
FR2077499A1 (cs) 1971-10-29
AT318670B (de) 1974-11-11
SE362264B (cs) 1973-12-03
BE742834A (cs) 1970-05-14
GB1290495A (cs) 1972-09-27

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