Specialized metallurgical processes – compositions for use therei – Compositions – Solid treating composition for liquid metal or charge
Patent
1994-07-25
1997-01-07
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Compositions
Solid treating composition for liquid metal or charge
75961, C22B 1243, C22B 702
Patent
active
055912478
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an agglomerated product containing, among others, fibers and a calcium derivative.
Document EP-A-0,272,242 describes an agglomerated product containing CaO and from 0.5 to 10% by weight of cellulose fibers as binder. According to this document the use of fibers makes it possible to increase, on the one hand, the resilience of the agglomerated product and, on the other hand, the reactivity of the agglomerated product.
Tests carried out by the Applicant have shown that an agglomerated product containing metallurgical dust and fibers exhibited a better resilience than an agglomerated product containing only metallurgical dust.
Metallurgical dust is intended to mean dust originating from industries or techniques which ensure the manufacture or the use of metals, it being possible for this dust to be metallic or otherwise, originating from ferrous or nonferrous metals.
Unexpectedly, the Applicant has noticed that it is possible to increase further the resilience of an agglomerated product containing metallurgical dust and fibers by adding an alkaline-earth metal hydroxide, in particular calcium hydroxide, to the said agglomerated product.
The agglomerated product according to the invention is an agglomerated product based on metallurgical dust additionally containing fibers and at least one hydroxide of an alkaline-earth metal.
In one embodiment the agglomerated product in accordance with the invention contains less than 75% by weight, advantageously from 0.5 to 20% by weight, preferably approximately 10% by weight of alkaline-earth metal hydroxide.
The weight content of fibers in the agglomerated product is advantageously lower than 20%, preferably between 0.5 and 10%.
In an advantageous embodiment the agglomerated product contains water, the moisture content of the product in accordance with the invention being advantageously lower than 20% by weight, preferably lower than 10% by weight, in particular between 5 and 10% by weight.
The alkaline-earth metal hydroxide is preferably calcium hydroxide such as a calcium hydroxide obtained by slaking of 1 part by weight of CaO or of CaO.MgO with approximately 0.7-0.8 part by weight of water, optionally in the presence of additives such as an amine or an aminoalcohol. The calcium hydroxide may therefore be in the form Ca(OH).sub.2.MgO or Ca(OH).sub.2.Mg(OH).sub.2.
Another subject of the present invention is a process for the preparation of an agglomerated product in accordance with the invention, in which a mixture of metallurgical dust, of fibers and of an alkaline-earth metal hydroxide is prepared and in which the said mixture is subjected to a compression.
Examples of fibers which can be employed in the product in accordance with the invention are: synthetic fibers such as glass fibers, carbon fiber, boron fibers, silicon carbide fibers, aramid, polyamide and phenolic fibers, polyalkyl (for example polyethylene, polypropylene) fibers, polyester fibers, acrylic, cellulosic, acetate, rayon and viscous fibers, fibers of vegetable origin such as sisal, jute, flax, cotton, wood, paper produced from wood, fibers of mineral origin such as asbestos, and metal fibers.
The fibers employed are preferably cellulosic fibers such as wood or paper fibers.
Metallurgical derivatives denote, among others, dry dust or dust of low moisture content (for example less than 10%) from the metallurgical industry, in particular from the iron and steel industry, such as slag, blast furnace dust, sludge obtained during the removal of dust from the fumes leaving converters (dust removal by a dry or wet route), and pulverulent or nonpulverulent products originating from catalysts containing metals employed in the chemical, in particular petrochemical, industry (cracking catalysts and the like).
As is known, the metallurgical derivative may be at the same time in the form of a dry (preferably pulverulent) powder and in the form of a sludge.
In the case of a powder, the mixture in the process according to the invention can be prepared merely by mixing or blending,
REFERENCES:
patent: 2865731 (1958-12-01), Crowe
patent: 4075027 (1978-02-01), Knill et al.
patent: 4093448 (1978-06-01), Eliseev
patent: 4336218 (1982-06-01), Kaas et al.
Dumont Philippe
Goffin Robert
Andrews Melvyn
Gunter Jr. Charles D.
Lhoist Recherche et Developpement S.A.
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