EP0346415A1 - Method for mixing ferrochromium slag in order to produce fire-resistant and chemically resistant fiber - Google Patents

Method for mixing ferrochromium slag in order to produce fire-resistant and chemically resistant fiber

Info

Publication number
EP0346415A1
EP0346415A1 EP19880910414 EP88910414A EP0346415A1 EP 0346415 A1 EP0346415 A1 EP 0346415A1 EP 19880910414 EP19880910414 EP 19880910414 EP 88910414 A EP88910414 A EP 88910414A EP 0346415 A1 EP0346415 A1 EP 0346415A1
Authority
EP
European Patent Office
Prior art keywords
slag
mixing
resistant
ferrochromium
sio
Prior art date
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.)
Withdrawn
Application number
EP19880910414
Other languages
German (de)
French (fr)
Inventor
Frans Heikki Tuovinen
Aarno Taneli Salervo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Outokumpu Oyj
Original Assignee
Outokumpu Oyj
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 Outokumpu Oyj filed Critical Outokumpu Oyj
Publication of EP0346415A1 publication Critical patent/EP0346415A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
    • C03C1/002—Use of waste materials, e.g. slags
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C13/00—Fibre or filament compositions
    • C03C13/06—Mineral fibres, e.g. slag wool, mineral wool, rock wool

Definitions

  • the present invention relates to a method for preparing ferrochromium slag, by adding SiO 2 and A1 2 O 3 bearing mixing agents, into a slag melt which can be defibrated into fibers resistant to high temperatures and highly alkaline conditions mainly for industrial use.
  • Ferrochromium slag is chromium-bearing magnesium-aluminiumsilicate, which is a by product from the process of metallic ferrochromium. It is typical of this slag that it is created in extremely reductive conditions in electric furnace smelting. Therefore it contains hardly any metal oxides that are reduced more easily than chromium oxide, nor does it contain easily evaporable components.
  • Ferrochromium slag is suited to be used as a raw material for special fibers resistant to high temperatures and alkaline conditions for the following reasons, among others:
  • the slag is homogeneous, once smelted and in the s o l i d state partly glazed material
  • the slag is an economically advantageous raw material.
  • ferrochromium slag used in the production of fibers is known from the Finnish patent application 845115.
  • the said application discloses two methods for mixing ferrochromium slag, with silicon oxide and aluminium oxide.
  • the purpose of mixing the ferrochromium slag is to change the physical properties of the slag melt so that the melt can be processed into fibers by means of generally known defibration methods.
  • the purpose of the mixing is to make sure that the desired properties for the end product are achieved. Therefore the defibration capacity of the slag melt cannot be improved for instance at the cost of the heat resistance of the end product fibers.
  • the present invention introduces an improved method for mixing ferrochromium slag, whereby it is possible to prepare such slag melt that the fibers produced thereof are resistant to high temperatures and alkaline conditions.
  • the fibers are mechanically strong and easily processible, which is of crucial importance with respect to their usability.
  • the mixing method of the present invention differs essentially from the one described in the FI patent application 845115 as for the mixing ratios and amounts of the employed agents.
  • the chemical composition of the slag melt to be defibrated, and naturally that of the end product fibers as well, is different and its properties better.
  • ferrochromium slag there are mixed SiO 2 , and A1 2 O 3 bearing mixing agents (such as quartz, anorthosite, kyanite, andalusite, bauxite etc.) so that the total SiO 2 /A1 2 O 3 ratio of the mixing agents is 0.8-1.85, and the MgO content of the mixed slag, reduced to the system MgOA1 2 O-SiO 2 , is 10-20% by weight.
  • the MgO, A1 2 O 3 and SiO 2 contents of the real multicomponent slag are accumulated up to 100% by maintaining the mutual relations of the contents.
  • the reduced MgO content of the slag melt to be defibrated is limited to below 20% by weight in order to ensure the defibrating capacity of the slag melt and above 10% by weight in order to prevent excessive increases in the defibration temperature of the slag melt.
  • the SiO 2 /A1 2 O 3 ratio between the mixing agents it is determined in order to secure the mechanical strength of the fiber.
  • the invention is also illustrated with reference to the appended drawing, which is a phase diagram of the system MgO -A1 2 O 3 -SiO 2 .
  • the drawing describes a composition of the FeCr slag, and the corresponding content range which falls within the scale of the present invention is shaded. If the composition of the FeCr slag is changed, the shaded area also changes, but the ratio between the mixing agents is maintained the same.
  • the amount of mixing agents added to the ferr ochromi um slag is 33-60% of the amount of the final slag.
  • the mixing takes place in a smelting furnace where the temperature and outflow of the melt are easily adjusted.
  • a suitable smelting furnace is for instance an electric furnace.
  • the ferrochromium slag mixed according to the method of the present invention can, by applying generally known defibration methods, be produced into special fiber with a better fire-resistance than with the known mineral or slag fibers. As for strength and processibility, this fiber is comparable to them or better. Its alkaline resistance is better as well.
  • the slag melt itself has a strong inclination for glazing.
  • the slag forms a completely glass like structure.
  • the created glass has a deep blue colour, and the fiber made thereof is light blue.
  • the chemical composition of a typical ferrochromium slag is: Fe 4.9%, Cr 9.0%, SiO 2 29.6%, CaO 3.1%, MgO 25.9% and A1 2 O 3 22.7% (percentages by weight).
  • the composition is: MgO 33.1%, A1 2 O 3 29.0% and SiO 2 37.9%.
  • the obtained composition range for the mixed slag is the shaded area of figure 1.
  • the initial composition of the ferrochromium slag is also indicated in the drawing.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Glass Compositions (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Inorganic Fibers (AREA)

Abstract

The invention relates to a method for preparing ferrochromium slag, by adding SiO₂ and Al₂O₃ bearing mixing agents, into slag melt which can be defibrated into fibers resistant to high temperatures and alkaline conditions. Mechani­ cally strong fibers are obtained when the SiO₂/Al₂O₃ ratio of the added mixing agents is within the range of 0.8-1.85 and the MgO content of the mixed slag, as reduced to the MgO-Al₂O₃-SiO₂ system, is within the range of 10-20% by weight.

Description

METHOD FOR MIXING FERROCHROMIUM SLAG IN ORDER TO PRODUCE FIRE-RESISTANT AND CHEMICALLY RESISTANT FIBER
The present invention relates to a method for preparing ferrochromium slag, by adding SiO2 and A12O3 bearing mixing agents, into a slag melt which can be defibrated into fibers resistant to high temperatures and highly alkaline conditions mainly for industrial use.
Ferrochromium slag is chromium-bearing magnesium-aluminiumsilicate, which is a by product from the process of metallic ferrochromium. It is typical of this slag that it is created in extremely reductive conditions in electric furnace smelting. Therefore it contains hardly any metal oxides that are reduced more easily than chromium oxide, nor does it contain easily evaporable components.
Ferrochromium slag is suited to be used as a raw material for special fibers resistant to high temperatures and alkaline conditions for the following reasons, among others:
- the slag is homogeneous, once smelted and in the s o l i d state partly glazed material,
- generally over 50% of the slag is covered by SiO2 and A12O3 which are needed in the manufacture of the slag melt,
- the K2O, Na2O and CaO contents of the slag are very low, which is of great importance with respect to both the fire resistance and the alkaline resistance of the fiber to be produced, the slag is an economically advantageous raw material.
The use of ferrochromium slag in the production of fibers is known from the Finnish patent application 845115. The said application discloses two methods for mixing ferrochromium slag, with silicon oxide and aluminium oxide. The purpose of mixing the ferrochromium slag is to change the physical properties of the slag melt so that the melt can be processed into fibers by means of generally known defibration methods. Moreover, the purpose of the mixing is to make sure that the desired properties for the end product are achieved. Therefore the defibration capacity of the slag melt cannot be improved for instance at the cost of the heat resistance of the end product fibers.
In order to make the ferrochromium slag melt so as to be well defibrated, the temperature dependence of its viscosity must be weakened, the surface tension lowered and susceptibility to crystallization reduced. All of these desired aims are achieved by mixing the slag so that it becomes acidic. In addition to this, it is important to reduce the activity of MgO in the slag melt.
In practical defibration tests, where ferrochromium slag was mixed according to the FI patent application 845115 so that the compos iti on of the mixed slag melt was set, in the phase diagram describing the MgO-A12O3-SiO2 system, within the crystallization range of cordierite it was observed that the slag melt was we l l defibrated. But the mechanical strength of the fiber was small and its processibility weak. In closer examinations the reason for this was found to be the crystalline components contained in the fiber.
The present invention introduces an improved method for mixing ferrochromium slag, whereby it is possible to prepare such slag melt that the fibers produced thereof are resistant to high temperatures and alkaline conditions. In addition to this, the fibers are mechanically strong and easily processible, which is of crucial importance with respect to their usability. The mixing method of the present invention differs essentially from the one described in the FI patent application 845115 as for the mixing ratios and amounts of the employed agents. The chemical composition of the slag melt to be defibrated, and naturally that of the end product fibers as well, is different and its properties better. The essential novel features of the invention are apparent from the appended patent claims.
According to the invention, to ferrochromium slag there are mixed SiO2, and A12O3 bearing mixing agents (such as quartz, anorthosite, kyanite, andalusite, bauxite etc.) so that the total SiO2/A12 O3 ratio of the mixing agents is 0.8-1.85, and the MgO content of the mixed slag, reduced to the system MgOA12O-SiO2, is 10-20% by weight. By reducing we here mean a calculation method whereby the MgO, A12O3 and SiO2 contents of the real multicomponent slag are accumulated up to 100% by maintaining the mutual relations of the contents.
In the mixing method of the present invention, the reduced MgO content of the slag melt to be defibrated is limited to below 20% by weight in order to ensure the defibrating capacity of the slag melt and above 10% by weight in order to prevent excessive increases in the defibration temperature of the slag melt. As for the SiO2/A12O3 ratio between the mixing agents, it is determined in order to secure the mechanical strength of the fiber.
The invention is also illustrated with reference to the appended drawing, which is a phase diagram of the system MgO -A12O3 -SiO2. The drawing describes a composition of the FeCr slag, and the corresponding content range which falls within the scale of the present invention is shaded. If the composition of the FeCr slag is changed, the shaded area also changes, but the ratio between the mixing agents is maintained the same.
In the mixing method of the present invention, the amount of mixing agents added to the ferr ochromi um slag, depending on the slag composition and the desired MgO content, is 33-60% of the amount of the final slag. The mixing takes place in a smelting furnace where the temperature and outflow of the melt are easily adjusted. A suitable smelting furnace is for instance an electric furnace.
The ferrochromium slag mixed according to the method of the present invention can, by applying generally known defibration methods, be produced into special fiber with a better fire-resistance than with the known mineral or slag fibers. As for strength and processibility, this fiber is comparable to them or better. Its alkaline resistance is better as well.
The slag melt itself has a strong inclination for glazing. When cooled in air from the molten state, the slag forms a completely glass like structure. The created glass has a deep blue colour, and the fiber made thereof is light blue.
The invention is further illustrated by means of the following example.
Example
The chemical composition of a typical ferrochromium slag is: Fe 4.9%, Cr 9.0%, SiO2 29.6%, CaO 3.1%, MgO 25.9% and A12 O 3 22.7% (percentages by weight). When reduced to the system MgO-A12O3-SiO2, the composition is: MgO 33.1%, A12O3 29.0% and SiO237.9%. When the slag is mixed according to the method of the present invention, the obtained composition range for the mixed slag is the shaded area of figure 1. The initial composition of the ferrochromium slag is also indicated in the drawing.

Claims

PATENT CLAIMS
1. A method for utilizing aluminium oxide and silicon oxide based ferrochromium slag in the production of fire-resistant and alkaline-resistant fiber materials, where the ferrochromium slag is mixed with SiO2 and A12O3 bearing mixing agents, c h a r a c t e r i z e d in that in order to improve mechanical strength and durability, the total SiO2/A12O3 ratio of the mixing agents to be added in the slag melt is adjusted to be within the range of 0.8-1.85, and simultaneously the MgO content of the mixed slag, as reduced to the MgO-A12O3-SiO2system, is adjusted to be within the range of 10-20% by weight.
2. The method of claim 1, c h a r a c t e r i z e d in that the amount of the added mixing agents is 33-60% by weight of the slag to be defibrated.
3. The method of claim 1, c h a r a c t e r i z e d in that the smelting and mixing of the raw materials of the molten slag is carried out in an electric furnace.
EP19880910414 1987-11-27 1988-11-18 Method for mixing ferrochromium slag in order to produce fire-resistant and chemically resistant fiber Withdrawn EP0346415A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI875238A FI78447C (en) 1987-11-27 1987-11-27 TILLSAETTNING AV FERROKROMSLAGG FOER FRAMSTAELLNING AV ELDFASTA OCH KEMISKT BESTAENDIGA FIBER.
FI875238 1987-11-27

Publications (1)

Publication Number Publication Date
EP0346415A1 true EP0346415A1 (en) 1989-12-20

Family

ID=8525485

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880910414 Withdrawn EP0346415A1 (en) 1987-11-27 1988-11-18 Method for mixing ferrochromium slag in order to produce fire-resistant and chemically resistant fiber

Country Status (4)

Country Link
EP (1) EP0346415A1 (en)
JP (1) JPH02502372A (en)
FI (1) FI78447C (en)
WO (1) WO1989004813A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5045506A (en) * 1989-07-31 1991-09-03 Alcan International Limited Process for producing mineral fibers incorporating an alumina-containing residue from a metal melting operation and fibers so produced
DE69812699T2 (en) * 1997-12-02 2004-03-11 Rockwool International A/S METHOD FOR PRODUCING GLASS-TYPE ARTIFICIAL FIBERS
SK286948B6 (en) * 1997-12-02 2009-08-06 Rockwool International A/S A process for production of man-made vitreous fibers and a briquette for their production
EP2857369A4 (en) * 2012-05-28 2016-03-23 Nichias Corp Si-Mg-BASED INORGANIC FIBER AND COMPOSITION CONTAINING SAME

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8904813A1 *

Also Published As

Publication number Publication date
FI78447B (en) 1989-04-28
FI78447C (en) 1989-08-10
WO1989004813A1 (en) 1989-06-01
JPH02502372A (en) 1990-08-02
FI875238A0 (en) 1987-11-27

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