Compositions: ceramic – Ceramic compositions – Composed of waste material
Patent
1989-08-17
1990-08-07
Dixon, Jr., William R.
Compositions: ceramic
Ceramic compositions
Composed of waste material
106789, C04B 506, C21C 700
Patent
active
049468111
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for processing iron silicate slags, by mixing with ferroalloy slag, to slag melt which can be defibrated into fire-resistant and chemically resistant high-quality fibers mainly for industrial use. The employed ferroalloy slag is ferrochromium slag or other slag of the similar type.
The utilization of slags, obtained as by-products from metal processes, for manufacturing slag wool is generally known. In industrial-scale production, the raw material is nearly always blast furnace slag. The smelting of the raw material mixture is generally carried out in a cupola furnace by means of coke, the defibration takes place in a four-wheel centrifugal machine and the typical manufactured products are heat insulation materials used in building.
Iron silicate slags have not been used as raw materials in the production of fiber products, irrespective of the many advantages and possibilities offered by these slags. This has mainly been due to the restrictions of the smelting unit, i.e. the cupola furnace, of the fiber production process. The fact is that the coke used in cupola furnace smelting tends to reduce the iron contained in the raw materials to metal, which leads to disturbances in the defibration process. There are also set limits to the grain size of the raw materials to be smelted in a cupola furnace: the raw materials must be in bulk size, and finely divided materials cannot be used. The reason for this is that the material bed to be smelted must be gas-permeable.
Electric furnace smelting, which during the past years has been adopted to fiber production, too, is changing the situation and has enabled the utilization of new raw materials, for instance the said iron silicate slags. The use of an electric furnace in the defibration of slag melt is introduced for instance in the FI patent 72502. Among the advantages of an electric furnace in the treatment of iron silicate melts, in addition to the fact that the creation of metallic iron is prevented, let us mention the possibility to controllably adjust the degree of oxidation of the iron contained in the melt which has a remarkable effect on the properties of the slag melt to be defibrated. If desired, it is possible to feed for instance iron silicate slag into an electric furnace in molten state, which may be very important from the economical point of view.
Iron silicate slags are created in the metallurgical industry for instance as by-products of copper and nickel processes. These slags differ from the rest of the common slag types particularly because of their high iron content. The slags may contain iron even 40% by weight. In addition to this, they are often finely granulated.
The use of iron silicate slags in fiber production is known from the FI patent application 845114, corresponding to U.S. Pat. No. 4,818,289. The said patent application discloses two ways for mixing iron silicate slag, so that the properties of the slag melt are changed by adding acidic mixing agents. According to this patent application, in order to manufacture fiber with a high heat resistance, an addition of 25-35% by weight SiO.sub.2 is mixed in the slag. In order to manufacture fiber with a lower heat resistance, an addition of 8-15% by weight Al.sub.2 O.sub.3 and 15-25% by weight SiO.sub.2 is mixed in the slag.
However, in practical defibration tests, where the aim was to produce a high-temperature resistant and chemically resistant fiber from iron silicate slags, it was observed that the slag melts produced according to the above described patent were defibrated in an unsatisfactory fashion. In order to achieve a high-quality fiber product, the iron silicate slag must be mixed to an essentially larger extent and with different mixing agents.
The present invention introduces an improved method for mixing iron silicate slag, which is essentially different from the method disclosed in U.S. Pat. No. 4,818,289, both as regards the used mixing agents and the supplied amounts. The chemical composition of the slag melt obtained as the result
REFERENCES:
patent: 4365984 (1982-12-01), Gee
patent: 4751208 (1988-06-01), Aoki et al.
patent: 4818289 (1989-04-01), Mantymaki
patent: 4818290 (1989-04-01), Tuovinen
Salervo Aarno T.
Tuovinen Frans H.
Dixon Jr. William R.
Hollenbeck Sue
Outokumpu Oy
LandOfFree
Method for mixing molten iron silicate with ferroalloy slag in o does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for mixing molten iron silicate with ferroalloy slag in o, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for mixing molten iron silicate with ferroalloy slag in o will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-960618