WO2001053546A1 - Method for casting ferro alloys - Google Patents

Method for casting ferro alloys Download PDF

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Publication number
WO2001053546A1
WO2001053546A1 PCT/NO2001/000007 NO0100007W WO0153546A1 WO 2001053546 A1 WO2001053546 A1 WO 2001053546A1 NO 0100007 W NO0100007 W NO 0100007W WO 0153546 A1 WO0153546 A1 WO 0153546A1
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WO
WIPO (PCT)
Prior art keywords
cooling bodies
vessel
ferro
filled
ferro alloy
Prior art date
Application number
PCT/NO2001/000007
Other languages
French (fr)
Inventor
Tore Valla
Original Assignee
Elkem Asa
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Elkem Asa filed Critical Elkem Asa
Priority to AU2001225595A priority Critical patent/AU2001225595A1/en
Publication of WO2001053546A1 publication Critical patent/WO2001053546A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
    • B22D11/0405—Rotating moulds

Definitions

  • the present invention relates to a method for casting of ferro alloys.
  • Ferro alloys such as ferrosilicon, ferrochromium and ferromanganese are conventionally cast into blocks using different casting methods, whereafter the blocks are solidified, crushed and sieved to obtain a saleable size.
  • ferro alloys are cast into moulds containing fines of the ferro alloy to be cast.
  • the ferro alloy solidifies as blocks which must be crushed and sieved in the same way as ferro alloys which have been layer cast.
  • ferro alloys are cast on movable casting belts. This gives a correct size in one direction, but also ferro alloy cast on casting belts must be crushed and sieved in order to obtain a saleable size. All the above mentioned casting methods result in relatively high losses of ferro alloys as fines. The amc unt of fines will vary somewhat from ferro alloy to ferro alloy, but will normally be in the range of 3 to 10 % by weight.
  • molten ferro alloy When molten ferro alloy is supplied to the vessel containing the cooling bodies, molten ferro alloy will fill the voids between the cooling bodies and solidify as a plurality of pieces having a size and shape corresponding to the voids between the cooling bodies. By properly selecting the size and the shape of the cooling bodies, the pieces of solidified ferroalloy will have a relatively even size whereby a saleable size of the pieces of ferro alloy is obtained directly without crushing.
  • the cooling bodies are preferably made from cast iron, steel or copper alloy. These materials have a sufficiently high density and a sufficiently high melting point. Further, these materials have a sufficiently high thermal capacity to obtain a fast cooling of the ferro alloy supplied to the vessel in order to cool the ferro alloy very fast to a temperature below the solidification temperature of the ferro alloy.
  • the high cooling rate results in a finer grain structure of the cast ferro alloy than what is obtained by using conventional casting methods.
  • the fine grained structure results in a mechanical stronger material that what is obtained by conventional casting methods.
  • Cast iron, steel and copper alloy also have a rather high thermal expansion coefficient resulting in that the cooling bodies expand when they are heated by the molten ferro alloy whereby the ferro alloy that fills the voids between the cooling bodies will crack.
  • the ferro alloy is, according to the present invention, expanded during solidification. The crushing takes place from the inside of the material. The cast pieces of ferro alloy can thus easily be separated from the cooling bodies and from each other.
  • the content of the vessel is emptied onto a grating or the like in order to separate the pieces of ferro alloy and the cooling bodies.
  • the cooling bodies can be separated from the pieces of cast ferro alloy by magnetic separation, by gravimetric methods or manually.
  • the cooling bodies may have equal size and shape, but cooling bodies having different shapes and/or sizes can also be used. It is preferred to use cooling bodies having such shape and size that they occupy between 30 and 70 % of the volume of the vessel when the vessel is filled with cooling bodies.
  • the cooling bodies are filled into vessel it is formed voids between the cooling bodies.
  • the cooling bodies are preferably filled into the vessel in random way, but the cooling bodies can also be arranged in a regular pattern by means of a robot or the like.
  • the size of the cooling bodies can also be varied in order to obtain a suitable size of the voids formed between the cooling bodies, but it is preferred to use cooling bodies where the largest dimension is between 200 and 300 mm and where the smallest dimension is between 10 mm and 20 mm.
  • Figure 1 is a vertical cut through a vessel for casting ferro alloy.
  • FIG. 1 there is shown a vessel 1 having a bottom 2 and sidewalls 3.
  • the vessel is filled with cooling bodies 4 made from steel which cooling bodies are cube-shaped and have a size of 100 mm x 100 mm x 100 mm.
  • the cooling bodies 4 are filled into the vessel in a random way whereby a plurality of voids are formed between the cooling bodies.
  • the voids will be of different size and shape, but will generally have such dimensions that the largest dimension of the voids are less than 100 mm and larger than 10 mm.
  • molten ferrochromium was tapped from a ladle (not shown).
  • the stream 5 of molten ferro alloy was placed centrally in the vessel 1 and the voids between the cooling bodies 4 were filled with molten ferrochromium 6.
  • the content of the vessel 2 was emptied.
  • the cooling bodies 4 were thereafter separated from the ferrochromium pieces by means of magnetic separation.
  • the pieces of ferrochromium had a size within preferred sales size and further crushing was thus not necessary.
  • the amount of fines produced during casting was very low, about 1.5 % by weight.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Glass Compositions (AREA)

Abstract

The present invention relates to a method for casting ferro alloys, where a vessel is filled with a plurality of cooling bodies in such a way that a plurality of voids are formed between the cooling bodies, which cooling bodies are made from a material having a melting point close to or higher than the casting temperature of the ferro alloy to be cast and which cooling bodies have a density equal to or higher than the ferro alloy to be cast. Molten ferro alloy is supplied to the vessel containing the cooling bodies and the cooling bodies are separated from the solidified ferro alloy.

Description

Title of Invention: Method for casting ferro alloys.
Field of Invention The present invention relates to a method for casting of ferro alloys.
Background Art
Ferro alloys such as ferrosilicon, ferrochromium and ferromanganese are conventionally cast into blocks using different casting methods, whereafter the blocks are solidified, crushed and sieved to obtain a saleable size.
In casting of ferrochromium and ferromanganese it is conventional to apply so-called layer casting. By layer-casting molten ferro alloy is cast on a bed having a surface area corresponding to the amount of ferro alloy that shall be cast in order to obtain a preset thickness of the cast layer. When a layer is solidified, a new layer is cast upon the solidified layer from the previous cast. The cooling rate when applying this method is very low as additional heat energy is supplied to the bed during casting of new layers on top of the bed. When the layered bed has been completely filled, the solidified bed of ferro alloy is broken by means of a fork-lift or the like and the blocks of ferro alloys are crushed and sieved. The crushing operation generates fines, which in the following is defined as ferro alloy having a particle size below normal sales size.
By mould casting, ferro alloys are cast into moulds containing fines of the ferro alloy to be cast. The ferro alloy solidifies as blocks which must be crushed and sieved in the same way as ferro alloys which have been layer cast.
Sometimes ferro alloys are cast on movable casting belts. This gives a correct size in one direction, but also ferro alloy cast on casting belts must be crushed and sieved in order to obtain a saleable size. All the above mentioned casting methods result in relatively high losses of ferro alloys as fines. The amc unt of fines will vary somewhat from ferro alloy to ferro alloy, but will normally be in the range of 3 to 10 % by weight.
It is further known to granulate ferro alloys, that is molten ferro alloy is divided into droplets which are solidified in water. In this method it is difficult to obtain granules having a satisfactory large size and it is further formed a large number of fine particulate granules. The granulation method does, however, have the advantage that no crushing is necessary after casting.
Disclosure of Invention It is an object of the present invention to provide a method for casting ferro alloys which can overcome the disadvantages of the known casting methods for ferro alloys and more particularly to provide a casting method for ferro alloys which substantially reduces the amount of fines.
Accordingly, the present invention relates to a method for casting of ferro alloys which method is characterized in that a vessel is filled with a plurality of cooling bodies in such a way that a plurality of voids are formed between the cooling bodies, which cooling bodies are made from a material having a melting point close to or higher than the casting temperature of the ferro alloy to be cast and which cooling bodies have a density equal to or higher than the ferro alloy to be cast, supplying molten ferro alloy to the vessel containing the cooling bodies and separating the cooling bodies from the solidified ferro alloy.
When molten ferro alloy is supplied to the vessel containing the cooling bodies, molten ferro alloy will fill the voids between the cooling bodies and solidify as a plurality of pieces having a size and shape corresponding to the voids between the cooling bodies. By properly selecting the size and the shape of the cooling bodies, the pieces of solidified ferroalloy will have a relatively even size whereby a saleable size of the pieces of ferro alloy is obtained directly without crushing. The cooling bodies are preferably made from cast iron, steel or copper alloy. These materials have a sufficiently high density and a sufficiently high melting point. Further, these materials have a sufficiently high thermal capacity to obtain a fast cooling of the ferro alloy supplied to the vessel in order to cool the ferro alloy very fast to a temperature below the solidification temperature of the ferro alloy.
The high cooling rate results in a finer grain structure of the cast ferro alloy than what is obtained by using conventional casting methods. The fine grained structure results in a mechanical stronger material that what is obtained by conventional casting methods. Cast iron, steel and copper alloy also have a rather high thermal expansion coefficient resulting in that the cooling bodies expand when they are heated by the molten ferro alloy whereby the ferro alloy that fills the voids between the cooling bodies will crack. In contrast to conventional crushing where the ferro alloy is compressed during crushing, the ferro alloy is, according to the present invention, expanded during solidification. The crushing takes place from the inside of the material. The cast pieces of ferro alloy can thus easily be separated from the cooling bodies and from each other.
When the temperature in the vessel has become sufficiently low in order to ensure that the ferro alloy is solidified, the content of the vessel is emptied onto a grating or the like in order to separate the pieces of ferro alloy and the cooling bodies. Alternatively the cooling bodies can be separated from the pieces of cast ferro alloy by magnetic separation, by gravimetric methods or manually.
The cooling bodies may have equal size and shape, but cooling bodies having different shapes and/or sizes can also be used. It is preferred to use cooling bodies having such shape and size that they occupy between 30 and 70 % of the volume of the vessel when the vessel is filled with cooling bodies.
The cooling bodies may have any shape. They may for instance have the form of cubes, prisms, spheres, pyramides, rods, cones, truncated cones, rings or polygons. The cooling bodies can also be linked together to form chains.
What is important is that when the cooling bodies are filled into vessel it is formed voids between the cooling bodies. The cooling bodies are preferably filled into the vessel in random way, but the cooling bodies can also be arranged in a regular pattern by means of a robot or the like. The size of the cooling bodies can also be varied in order to obtain a suitable size of the voids formed between the cooling bodies, but it is preferred to use cooling bodies where the largest dimension is between 200 and 300 mm and where the smallest dimension is between 10 mm and 20 mm.
Short description of the drawing
Figure 1 is a vertical cut through a vessel for casting ferro alloy.
Detailed description of the invention
In figure 1 there is shown a vessel 1 having a bottom 2 and sidewalls 3. The vessel is filled with cooling bodies 4 made from steel which cooling bodies are cube-shaped and have a size of 100 mm x 100 mm x 100 mm. The cooling bodies 4 are filled into the vessel in a random way whereby a plurality of voids are formed between the cooling bodies. The voids will be of different size and shape, but will generally have such dimensions that the largest dimension of the voids are less than 100 mm and larger than 10 mm.
In one test molten ferrochromium was tapped from a ladle (not shown). The stream 5 of molten ferro alloy was placed centrally in the vessel 1 and the voids between the cooling bodies 4 were filled with molten ferrochromium 6. when the cast ferrochromium was solidified the content of the vessel 2 was emptied. During emptying the mixture of cooling bodies 4 and cast pieces of ferrochromium broke up. The cooling bodies 4 were thereafter separated from the ferrochromium pieces by means of magnetic separation. The pieces of ferrochromium had a size within preferred sales size and further crushing was thus not necessary. The amount of fines produced during casting was very low, about 1.5 % by weight.
The used cooling bodies were examined for wear and partial melting, but no wear or partial melting was found. The cooling bodies were therefore recycled for use in further castings. Even after a plurality of castings no wear was observed on the cooling bodies. The consumption of cooling bodies by the method of the present invention is therefore very low.

Claims

CLAIMS:
1. Method for casting ferro alloys, ch a racte rized i n that a vessel is filled with a plurality of cooling bodies in such a way that a plurality of voids are formed between the cooling bodies, which cooling bodies are made from a material having a melting point close to or higher than the casting temperature of the ferro alloy to be cast and which cooling bodies have a density equal to or higher than the ferro alloy to be cast, supplying molten ferro alloy to the vessel containing the cooling bodies and separating the cooling bodies from the solidified ferro alloy.
2. Method according to claim 1, c h a ra cte ri ze d i n that the vessel is filled with cooling bodies having such shape and size that the cooling bodies occupies between 30 and 70 % of the volume in the vessel when the vessel is randomly filled with cooling bodies.
3. Method according to claim 1, c h a ra cte rized i n that the vessel is filled with cooling bodies having a size where the largest dimension is between 200 mm and 300 mm and where the smallest dimension is between 10 mm and 20 mm.
4. Method according to claim 1, ch a ra cte rized i n that the vessel is filled with cooling bodies made from cast iron, steel or copper alloy.
5. Method according to claim 1, ch a ra cte rized i n that the vessel is filled with cooling bodies having a shape selected among cube, prism, sphere, pyramide, bar, cone, truncated cone, ring or polygon.
6. Method according to claim 1, c h a ra cte rized i n that the vessel is filled with cooling bodies which are connected to each other.
7. Method according to claim 6, ch a ra cte ri zed i n that the vessel is filled with cooling bodies in the form of chains.
8. Method according to claim 1 , c h a ra cte rized i n that the cooling bodies are separated from solidified ferro alloy by magnetic separation.
9. Method according to claim 1 , c h a ra cte ri zed i n that the cooling bodies are separated from solidified ferro alloy by sieving.
10. Method according to claim 1, c h a ra ct e ri ze d i n that the cooling bodies are separated from solidified ferro alloy by gravimetric methods.
PCT/NO2001/000007 2000-01-18 2001-01-10 Method for casting ferro alloys WO2001053546A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001225595A AU2001225595A1 (en) 2000-01-18 2001-01-10 Method for casting ferro alloys

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO20000236A NO310707B1 (en) 2000-01-18 2000-01-18 Procedure for Casting Ferro Alloys
NO20000236 2000-01-18

Publications (1)

Publication Number Publication Date
WO2001053546A1 true WO2001053546A1 (en) 2001-07-26

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ID=19910610

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PCT/NO2001/000007 WO2001053546A1 (en) 2000-01-18 2001-01-10 Method for casting ferro alloys

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AU (1) AU2001225595A1 (en)
NO (1) NO310707B1 (en)
WO (1) WO2001053546A1 (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1323282A (en) * 1971-02-04 1973-07-11 Norton Co Production of fused abrasives
GB1383929A (en) * 1971-04-19 1974-02-12 Treibacher Chemische Werke Ag Process for the production of crystalline abrasive material
GB1557990A (en) * 1976-11-29 1979-12-19 British Steel Corp Temperature control of molten iron or steel
EP0325750A1 (en) * 1988-01-18 1989-08-02 Heckett Holland B.V. Metallic coolant for a metallurgical bath, method of cooling using the coolant, method of manufacture thereof
GB2263707A (en) * 1992-01-24 1993-08-04 Steeltech Limited A steel waste treatment system
US5817164A (en) * 1994-03-04 1998-10-06 Aktsionernoe Obschestvo Zakrytogo Tipa "Intermet-Service & Co." Method and apparatus for making feedstock for steel making

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1323282A (en) * 1971-02-04 1973-07-11 Norton Co Production of fused abrasives
GB1383929A (en) * 1971-04-19 1974-02-12 Treibacher Chemische Werke Ag Process for the production of crystalline abrasive material
GB1557990A (en) * 1976-11-29 1979-12-19 British Steel Corp Temperature control of molten iron or steel
EP0325750A1 (en) * 1988-01-18 1989-08-02 Heckett Holland B.V. Metallic coolant for a metallurgical bath, method of cooling using the coolant, method of manufacture thereof
GB2263707A (en) * 1992-01-24 1993-08-04 Steeltech Limited A steel waste treatment system
US5817164A (en) * 1994-03-04 1998-10-06 Aktsionernoe Obschestvo Zakrytogo Tipa "Intermet-Service & Co." Method and apparatus for making feedstock for steel making

Also Published As

Publication number Publication date
NO20000236D0 (en) 2000-01-18
AU2001225595A1 (en) 2001-07-31
NO310707B1 (en) 2001-08-20
NO20000236L (en) 2001-07-19

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