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)
• Inorganic Fibers (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8525485

Family Applications (1)

Country Status (4)

Families Citing this family (5)

• 1987
  • 1987-11-27 FI FI875238A patent/FI78447C/fi not_active IP Right Cessation
• 1988
  • 1988-11-18 EP EP19880910414 patent/EP0346415A1/de not_active Withdrawn
  • 1988-11-18 JP JP63509448A patent/JPH02502372A/ja active Pending
  • 1988-11-18 WO PCT/FI1988/000188 patent/WO1989004813A1/en not_active Ceased

Non-Patent Citations (1)

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