DE1926642C3 - Process for the production of lightweight refractory bodies from silicon carbide with aggregate - Google Patents

Description

The invention relates to a VerLnren for the manufacture lung easier refractory body ge <pulvcri- let the fine-grained or profiled S.iiciumcarbid "nil minde- Itens an aggregate with addition of a Bindetnittcls are mixed, after which promoted the wetted mixture into a mold, compacted and dried will. It is known to use powdered or fine-grain silicon carbide in the production of highly refractory bodies for the inner lining of industrial furnaces, crucibles, etc., to which aggregates such as cristobalite and / or ouarzite and binders such as polysilicic acid or alkali silicates are added. Such a mass is conveyed by means of conveying devices to a compression molding device, where the compacts are produced. The compacts then pass through a drying line which is shielded from the outside and in which they are dried at a high temperature, for example between 900 and 1600 ° C.

Although such bodies have a high resistance to fire, their breaking strength is low, which is evident from numerous early fractures. Furthermore, the burn-off properties are not yet sufficient either. Above all, however, the known refractory bodies have a relatively high weight, which hinders and complicates both the production and the subsequent handling of the body, e.g. B. in the creation of refractory linings in the furnaces.

The object of the invention is to create a new method for producing high-strength bodies which, in addition to having high or even better resistance to fire, have a significantly lower weight than conventional bodies and whose resistance to breakage and erosion are improved.

The solution to the problem consists in the fact that perlite is added as an additive in the process mentioned in the introduction.

This makes it possible to produce perforated bodies which have an extremely low weight compared to comparable expensive bodies made of silicon carbide, and the weight reduction achieved with perlite can be up to 50.degree. Furthermore, breaking strength and burning resistance are

ίο significantly improved, and there is an improved water resistance in accordance with the invention Process produced bodies given.

The new aggregate perlite, which has a very low specific weight, is added or fine-grained form to the other ingredients of the mixture. According to known ones Process features are then proceeded in such a way that the mixture is whirled up or transferred into a floating-like state, that the binding agent

ao tcl into the slowly sinking mixture \ .ciuüst and that the collected mixture, wetted with binding agent, laterally by means of a screw conveyor conveyed away and in a Formgebungseinrichiung is given.

»5 Another weight reduction and one opposite known values increased hiizeah defense or heat re-radiation standards hei hochfeueriesteii Bodies is achieved according to a further feature of the invention in that the perlite material from the edge area of the set shaped body '; is melted out. Let this process; steer them! -, depending on the desired depth of melt.

For the body produced according to the invention Furthermore, a heated drying system is no longer necessary.

because sufficient and rapid drying of the body can also be achieved at room temperature. At the same time, however, a heated drying system can be used.

The invention is illustrated below using an exemplary embodiment explained in more detail. For this purpose, the drawing shows a device for carrying out the process according to the invention Procedure in longitudinal section.

The apparatus which does not form part of the invention will first be described. Via feed devices 1 and 2, the conveying speeds of which can be regulated for the purpose of metered feed, wc:.: ;;: the individual good ingredients to be mixed with one another are fed to a mixing funnel 3. This can / to achieve good mixing of the material to be mixed through a rotatable bearing 4 u ;;; its vertical axis can be rotatably mounted, the rotational movement being achieved by a motor, the pinion of which engages in a ring gear on the funnel 3. Motor and ring gear are omitted for the sake of simplicity. At the outlet, that is to say at the narrowed end of the funnel, there is a vibrating screen 5, which is set in a vibrating motion via a linkage 6 by a motor 7 attached to a bracket 15. The rippling movement must be such that the mixed material falling through the sieve has an extremely low degree of density underneath the sieve, i.e. it assumes a whirled or sluggish state, so that the material has a very low sinking speed.

After passing through the sieve 5, the through-flowing material arrives in a falling chamber 8, which is designed as a vertical cylindrical body supported by feet 14. In the wall of the chamber 8

are fed via feed lines 10, onto which the coming mixture is guaranteed to be evenly

nozzles 9 aligned with the sinking Guisirom are demittel wetted,

arranged for the injection of the liquid Uindemil- The evenly wetted mixture is caught in net. The lower end of the fall chamber 8 forms the collecting space II and is conveyed by the conveyor Collecting space 11, which is funnel-shaped into a worm gear 13 of a conventional shaping device n / A! 12 with a discharge conveyor located therein for the production of the moldings. Connecting screw c 13 passes. That reached to the screw, the briquettes are ßend about at room temperature Mixture wetted with binding agent is then dried, whatever the door, drying in the air but not shown further, made in a Prcßeinrich- or in a temperature-controlled room for the production of moldings. can be io. But it can also be heated

The sequence of the method according to the invention can be used for the drying system, with a

Production of a highly refractory body, the min drying temperature of 200 to 300 ° C with 2 to

at least an extremely low weight and an improved 3 m / s drying air circulation with a decreasing

The relative humidity is 92 to 50 *. «

gender: 15 is appropriate. The risk of surface risk

Powdered or granular is not used as the starting material on the bodies.

For special purposes it is advantageous to use the drying device 1 in the rotating funnel 3 countered or tied body, z. B. stones or will practice. Plates are subjected to a special heat treatment via the feed device 2 all aggregates fed in at the same time, subject to ao. This consists in the fact that the Perlitemawobei for each aggregate a separate conveyor material from the edge area of the bound grain direction 2 is provided. The aggregates are best personally melted out, whereby the kaid bohen among other things from the known Gcsteinsmeh- rich becomes porous. This has c. '. E more weight mines such as B. cristobalite and / or Qui.fzit and / or derung as well as an increased resistance to anti-etching of the bloated Mica. 25 refractory bodies result. The meltdown:

According to the invention, the new aggregate is controllable as required.

Perlite with a specific gravity. 70 kg / m ^{: 1} A recipe is given below, which

or i-iwa added to this value. The perlite can be added to the process according to the invention.

also-; is used as sole aggregate. The proportions by weight of silicon carbide, perlite, quartz / i:

After thorough mixing in the funnel 3, cristobalite and binding agent are mixed, the mixture is released through the vibrating sieve in a ratio of 2: 2: 1: 3 . very quickly assumes a state that is similar to floating or floating. This binds, the processing of the mixed material wetted with binding agent (ine very low density of the mixture up to the shape of the grain, whose sinking speed is low. Through 35 pers.

the nozzles 9 aligned with this downflow will further advantages of the invention are that

then the binding agent is injected into the chamber 8, with this method no dust and odor

in such a way that the liquid binder, e.g. B. Poly- svungen occur, with the finished refractory

Silicic acid or alkali silicates, in a body known per se, with strong heat exposure, almost odor-wise is highly fogged. This leaves 40 lost. Also with this body, hit / .e-

is enough that the fail chamber does not show any signs of soot.

Claims (4)

Patent claims: 1. A method for producing light refractory bodies, according to which powdered or fine-grained silicon carbide and at least one aggregate are mixed with the addition of a binder, whereupon the wetted mixture in a form is conveyed, compacted and dried, characterized in that as Perlite aggregate is added. 2. The method according to claim 1, characterized in that the mixture is whirled up or transferred into a floating-like state, that the binding agent is atomized into the slowly sinking mixture in a manner known per se and that the collected mixture wetted with binding agent is conveyed away to the side by means of a screw conveyor. 3. The method according to claims 1 and 2, characterized in that the means of a Shape formed body is dried at about room temperature or at 200 to 300 ° C. 4. Method according to the, \ nproverbs 1 to 3, thereby characterized in that the perlite material is melted out of the edge area of the set molding.