CH234321A - Process for manufacturing agglomerated refractory products. - Google Patents

Description

Process for the manufacture of agglomerated refractory products. In the manufacture of agglomerated refractory products, from molten and solidified refractory materials, then ground, to agglomerate fine grits under pressure, mixed with fines obtained by fine grinding, the vitreous material of these fines being able to constitute the only binder necessary for the agglomeration.

The agglomerate coolers of this type obtained so far have the serious disadvantage of having their resistance to collapse under load at high temperature, limited by the nature of this glass serving as binder, which constitutes an element of less resistance.

The subject of the present invention is a process for the manufacture of agglomerated refractory products, which makes it possible to remedy this drawback and to obtain agglomerated refractories which are notably more resistant to sagging under load at high temperature. It proceeds to agglomerate under Pressure and by cooking a mixture of granules and Eines, obtained from molten, solidified and crushed refractory materials. It is characterized in that, for Bette agglo@meration, seeds from molten im- ractary, normally solidified, are used with: des Eines adopts the vitreous phase presents a higher pyrometric resistance than that of the seeds.

In the baked refractory product, the connection between the grains is ensured by the glass of the Eines which serves as a binder, the fines being welded between them and to the grains because the glass which they contain has Bubi at least -Lm softening superficial during the firing of the refractory.

A first way to obtain the vitreous material of higher pyrometric resistance than that of the vitreous maure of the seeds, can consist in Bonneting the refractory constituting the Eines with a composition which confers on its glass a point of ra- softening supA-laughing ä. that of the glass of the refractory constituting the grains. The second means may consist of ä. to subject the refractory constituting the fines, during a casting operation or after it, to a "quenching" or "astonishment" treatment, or the like, making its glass more rich in material with high pyrometric resistance than it refractory constituting .the seeds. The two means indicated above can also advantageously be used together in combination.

It is thus possible to manufacture agglomerated refractories which combine the advantage of presenting an excellent behavior thanks to the solid skeleton constituted by the crystals of the basic molten refractory, the advantage of having their sag point under eha.rge ä. high temperature raised to a value distinctly higher than that observed on agglomerates in which the fines come from the same refractories, as regards their composition and their treatment, as the grainlets.

So the first cry where it is a question of agglomerating the grains coming from the molten refractory of hast with fines coming from a molten refractory of different composition, adopts the glass, after normal cooling, is at higher pyrometric resistance, the constituent material of the fines is chosen such, with respect to the constituent material of the seeds, that their association gives mixtures particularly well suited to the agglomeration operations; The advantage of reducing to a minimum the consumption of materials with very high pyrometric resistance, and particularly from Gelles dopt, the supply is difficult or contentious.

In Gas where it is a question of agglomerating the grains coming from the refractory of bare melted and normally solidified with fines obtained from refractory maueres, ires which can moreover come from a melting bath identical to that of bare refractory, and which Fon subjects to a treatment of

"Tempered", year can realize this tra.itement, sofft in particular during dune lee casting operation, for example by pouring the molten refractory on a centrifugal disc sprinkled with water, sofft after the casting operation. This "tempering" treatment has the effect of hastening the solidification of the refractory constituting the fines, while preventing crystals, in particular crystals with high pyrometric resistance, from forming or developing in a way important; it thus has the result of increasing cori@relatively the content of the vitreous phase in mati@re with high pyrometric resistance. Here, to be an example, how the first process of the invention can be executed <I>Example 1:</I> 0n agglomerates together, under pressure and by cooking, chips coming from a refractory molten at based on corundum and zirconia, which, after normal cooling, is distinguished by a glass with a particularly high softening point. The agglomerate manufactured from this faron presents a point of affais.sement under load very similar to that observed on the molten and cooled refractory norma.lement, based on corundum and zireone. This process thus makes it possible to obtain almost entirely the qualities of refractories based on corundum and zireene, while reducing the quantities of zirconia used.

<I>Example 2:</I> 0n agglomerated together, under pressure and by cooking, of: seeds from a molten refractory based on corundum and mullite, normally cooled, and fines from the same fusion, but obtained after tempering treatment, carried out by the action of water and/or cold air during or after casting, so as to limit the development of eroundum and mullite eristals . This "tempered" may-iere contains a more aluminous glass than that of the same untempered product and, consequently, presenting a strongly increased pyrometric resistance. By using this particularly alumina-rich glass as a binder, agglomerates are obtained which, in practice, have proved to be much more resistant to collapse under load. high temperature as if the binder were the glass of the same untempered refractory. Example, <I>3:</I> 0n a.gglomerates together, under pressure and by cooking, grains from a molten refractory based on corundum and mullite, normally cooled, and Eines from a molten refractory based on corundum and zirconia, but obtained after a quenching treatment carried out by aetion of water and/or cold air, during or after casting, so as to limit the development ment, crystals of corundum and zirconia or any other co: mpose. Tempered mauve gelte contains a glass richer in highly refractory elements than that of the same product which is not tempered and, consequently, presents a greatly increased pyrometric resistance. By using as binder c6 glass particularly rich in alumina and zirconia, one obtains agglomerates whose resistance to sagging under load at high temperature is, in practice, much more 616v66 than if the binder was the glass of the refractory constituting the grains or that of the refractory constituting the Eines and not tempered.

Claims (5)

CLAIM Process for the manufacture of agglomerated refractory products, according to which an agglomerate, under pressure and by cooking, a mixture of grains and fines, obtained from molten, solidified and ground refractory materials, characterized in that that one employs, for this agglomeration, granules coming from a molten refractory, solidified normally, with Eins whose vitreous phase presents a higher pyrometric resistance than that of, seeds. SUB-CLAIMS: 1. Process according to claim, characterized in that fines are used originating from a refractory other than that of normally cooled granules, and whose composition is such that, after this normal cooling, its glass has a higher softening point than that of the refractory constituting the grains. 2. Pro.cedg s-according to the claim, characterized in that Fon uses fines from a poured refractory, the solidification of which has been gtg hätge by an energetic cooling, having the result of enriching its glass. mauere with high pyrometric resistance. 3. Process according to claim and sau-claim 2, characterized in that los refractory masses used for the pr6pa- rahon, grainettes and Eines come from melting baths of composition @d: different. 4. Process according to claim and sub-claim 1, characterized in that the grains come from a fused refractory based on corundum and mullite and the grains come from a fused refractory based on corundum and zirconia. 5. Process according to claim and sub-claim 2, characterized in c6 that the seeds come from a melted refractory bare of corundum and mullite and the fines of a melted refractory and suddenly cooled co: mpose alumina, and silica. G. Process: according to claim and sub-claims 2 and 3, characterized in that the grains come from a molten refractory, ä, base of corundum and mullite, and the fines from a suddenly cooled molten refractory - ment with alumina and zirconia bare.