CH239899A - Process for manufacturing basic refractory bodies and basic refractory body obtained by this process. - Google Patents

Description

Process for manufacturing basic refractory bodies and basic refractory body obtained by this process. The main refractory materials used for making basic coatings are dolomite and magnesia, generally used, either in the form of bricks, or in the form of rams obtained. by hot mixing of the refractory with dehydrated tar, followed. , of a cold kiln tamping, suffered by the mixing of the refractory with slag and the introduction of this mixture into a hot kiln.

The making of these coatings requires a relatively long time, in some cases they must be shaped beforehand into bricks, which is costly. We have recently developed the use of ground dolomite, devoid of any agglomeration material, which has constituted an interesting progress, but the refractory mass thus constituted cannot be suitable in all cases, especially when these are kilns operating at high temperature or kilns operating intermittently for which the spontaneous extinction of the dolomite during cooling causes disaggregation and, consequently, the loss of the gar weaving.

It is however possible to attenuate or avoid this @decomposition by adding oxides such as Fe@O3-AlZO3-SiO2, but the melting point is greatly lowered. It should, moreover, be noted that, even if the temperatures achieved do not seem to require it, there is always. interest in using the most refractory material, which allows a lowering of the cost price by increased production "due to the fact that the progress of the Tour can be accelerated without risk of melting of the refractory; and that the loss of time due to rep.aratons are reduced.

Up to this day, magnesia has been used either in the form of bricks, in the form of piss, in tar agglomerates, or with other substances such as #elässe, l.a d# egtrine, alumina, sodium silicate, magnesium chloride, etc.

Although the melting point of magnesia is 616 v6 more by almost 500 than that of dolomite, its use has not variations & te@mperature and shocks, Jkaillent easily and are of a cost price .eteve. Magnesia-chrome bricks, less prone to this kaillage, cannot be used in parts in contact with the bath. The piss produced to date is friable, heterogeneous and subject to landslides.

The present invention, which makes it possible to entirely eliminate the drawbacks indicated above, comprises a process for the manufacture of basic refractory bodies and a basic refractory body obtained by this process. Such a Body can just as well be a Part of a construction made on site, as an independent pike or a construction element; it can, for example, be a kiln lining, a volle, a hearth, a side wall, a burner, a refractory brick, a spout, a plug, a ferrule, etc.

The process of the invention is characterized in that, when compressed dry, without binder and cold, a powder will form at least for its most part of fine-grained ground calcined magnesia, until obtaining, a compact mass, then in that the latter is subjected to the action of heat, which progressively transforms it into a monolith.

The @compression of the powder can be carried out by dama@ge.

In the case where a furnace lining or Mablis elements are to be fabricated directly in a furnace, the heating may result from the actual operation of the furnace; in the case of piken such as bricks, which may be subjected to manipulations before being installed in a kiln, these piken will be subjected to special heating after tamping, die magnesia.

The mabo-nesia used as raw material will preferably be ground until obtaining grains with a maximum diameter of 4 mm and flour; e1.16 could Ure melan.gee with a certain quantity of lime, this, the latter being sofft in the free state, sofft in the combined state, for example in the form of double oxide of magnesia and lime CaO, Mg0, commonly sold in RTI ID="0002.0278" WI="3" HE="3"LX="1422" LY="363"> 1e: commerce under the name of frittWet dolomite from ca .lcination i die raw dolomite, which is a double carbanate of lime and magnesia CaMg(C03)' (or C03Mg, C03Ca).

A certain percentage of iron or steel wires (up to around 20%) can be useful for the construction of the sides, burners, vaults and certain floors.

The basic refractory body obtained by the first proced-e of the invention is characterized in that it is formed, at least for its greater part, of agglomerated magnesia with --ec and sauces, binder.

In the case where this Body is a furnace refractory lining, it becomes extremely hard, resists high temperatures, temperature variations, and does not disintegrate when it cools. The present invention allows, for the first time, the application of a basic refractory lining, comprising no agglomerate, to furnaces whose lining is relatively thin and where the melting operations do not follow one another. without interruption; las colds due to stops, die at night or, Sunday, for example, does not lead to the decommissioning by disintegration of .1a refractory mutiere. The process of the invention can be applied to the manufacture of a large number of refractory bodies, of which the following is a list of the main ones, by way of example: Furnace burners. arid or basic; Various linings, uprights of all basic furnaces, used for melting cast iron, steel or all alloys or ferro=alloys, such as: Induction furnaces at any frequency, electric furnaces, type lathes (arc, radiation, resistanoes, etc.) rotating or fixed; Thomas converters, mixers, cupolas; Lining of cement kilns, etc.; All products, fago:unes refractories, such as bricks, nozzles, tampans, ferrules, etc. The process according to the invention is suitable for the manufacture of floors, burners, vaults, walls and all parts of: the lining of all industrial furnaces; it allows, in addition to a faster confection, a lowering of the prig @de returns both by 1'economy of labor-@d'ceuvr-e that by the reduction, frass -d'maintenance.

It makes it possible to produce refractory linings which, in the heart, of the operation of the furnaces, present a great solidity, resist ä. very high temperatures, remain insensitive to temperature variations and are not subject to erosion on contact with the air.

See how the process of the invention can be carried out in practice: Example <I>1:</I> Constructio:n of a: coating -of a rotary kiln for melting @of heat and @of @ steel.

The magnesäe, ground:e dan:s! a suitable grinder until a grain size of 4 mm is obtained. of large diameter and flour, is mixed with a certain potential for heating in the free state, or combined without the ratio

by weight egcede 0.80.

The coating is cold rammed by successive layers between two reinforcements, with incorporation of iron or steel wires in the mass. Subsequent firing turns this assembly into a solid mass, very refractory and very hard, able to withstand very high temperatures and prolonged shutdowns without disintegration.

Example <I>2:</I> Burner heads, pedestals and vaütes are constructed in the same way as @analague ee@hl#9,described in example 1 p-ar,damage between two reinforcements . However, it may be useful to incorporate iron or steel reinforcements of appropriate shapes into the refractory mass. Example <I>3:</I> The coating of an induction lathe is made in an urn, analogous to Gelle: described in example 1, with the exception of 'de chaug ä, 1' Free or -combined state @depending on the operating conditions of the oven. The incorporation of iron or steel wires in the mass is not necessary. cold; 1e pro,ced#6 makes it possible to completely or partially eliminate the use of @magn & sie bricks. -During the travädl, .1ä Sole res@e compact, hömägenä and smooth. RTI ID="0003.0274" WI="14" HE="4" LX="1290" LY="672"> Example <I>5:-</I> Los. pieces such as bricks, nozzles, tampans, ferrules, etc. -were shaped and, tamped by hand or by machine, could be subjected to a. slow and gradual heating up to a temperature of 1200 mihimum. The temperature and idure of @cooking are regulated @ according to the @dimensions of the products, how @n.6s and the thickness @eur @of.sintering @desirö_es. The ob- tonus bodies, which do not disintegrate by spontaneous egtin ction to air, can. eire, put in storage to be used later as and when. to measure,needs.

'W- The process @of ixtveutio:n tröüve:therefore applications -for all types of flowers, subject to a few modaJites @of egecuton, according to the!se!various constructions; of ovens and the uses envisaged: by Ges: last.

Claims (7)

CLAIMS: I. Proeecle,of workmanship,of body. basic refractories, characterized in that when compressed dry, without binder, and cold, a powder forms at least for its largest part of fine-grained ground calcined magnesia, until obtaining, of a compact mass, then in that Fon subjects this last to the action of heat, which progressively transforms it: into an oläthe. II. Basic refractory body manufactured by the first pro: cede according to Ja claim I, characterized in that it is shaped; at least, for @s:a plus Brande Part, @of magnesäe agglomerated dry and without binder. SUB-CLAIMS: 1. Process according to claim 1, characterized in that the powder is compressed by pressing. 2. Process according to claim I and sub-claim 1, for the manufacture of oven parts, in. the kiln itself, characterized in that the powder is placed in place in the kiln, then in that the composite mass obtained is subjected to the action of heat, by means of setting: oven operation off. 3. P'rocede according to claim I, charac- t6ris6 in that before co: mprimer, powder, year has in it frames! metallic so that they are coated in the compact mass. 4. Process according to vend.ication I and sound-claim 3, earacterise in that said .armatures are metallic fil.s. 5. Process according to claim I and sub-claim 3, characterized in that the first weight of said reinforcements does not exceed 20% of the total weight of the compact mass. 6. Process according to claim 1, cara.c- -#erise in that Von compresses the powder in successive layers. 7. Process according to claim 1, characterized in that ground magnesia is used to an as-is degree consisting of grains with a maximum diameter of about 4 mm and flour. B. Process according to claim I, charac- teris6 in that Fon uses a powder formed, at least in part. of magnesia and lime mixed, the 1st ratio by weight remaining less than 0.80. 9. Process according to claim I, for the manufacture of separate pieces, characterized in that Fon slowly and progressively heats the compact mass up to 1200 C at m:o:ins. <B>10.</B> Process according to claim 1 and sub-claim 1, for the manufacture of separate parts, characterized in that the grinding is carried out by machine. 11. Refractory body according to Claim II, characterized in that it also contains lime, the first ratio by weight being less than 0.80.