Metallurgical apparatus – Process
Patent
1982-11-19
1984-11-06
Rutledge, L. Dewayne
Metallurgical apparatus
Process
266281, F27D 116
Patent
active
044808208
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to metallurgy and foundry engineering and particularly concerns a method of lining a metallurgical assembly.
2. Description of the Prior Art
An important problem encountered by those skilled in the art when developing a technology of lining metallurgical assemblies, e.g. induction furnaces consists in increasing stability of the lining with a simultaneous reduction of expenses required for manufacturing said lining.
The process of lining a metallurgical assembly is generally carried out as follows (see M. G. Trofimov, Futerovka induktsionnykh pechei, Moscow, "Metallurgia", 1968, pp. 129-132). First, a bottom is lined using a conventional method, following which a gauge for forming an inner wall of the future lining (a crucible) is mounted on said bottom. The space provided between the gauge and a corresponding element of the assembly, forming an outer wall of the lining (in the induction furnace this element is an induction heater) is filled with a free-flowing lining mass, e.g. with quartz sand containing binding additives. Following this the lining mass is compacted using various methods. The lining thus obtained is then sintered to increase its strength and resistance to the effect of a melt.
It should be noted that since the lining serves as a separating barrier between the melt and the cooled induction heater of the furnace, three zones having different degrees of sintering are present therein, the existence of these zones being caused by a relatively high temperature gradient in the direction of the thickness of said lining. The lining of the first zone (which is the closest to the melt) is the most sintered and the strongest one. The lining of the second (intermediate) zone, due to a lower temperature, is sintered to a lower degree than in the first zone and is less strong. In the third zone (abutting with the induction heater of the furnace) of the lining there is almost no sintering since individual grains of the refractory material are practically not bound between themselves.
In the course of lining the steps of filling and compacting the lining mass must be carried out in such a manner as to ensure:
(a) the highest degree of compaction in the first zone in order to obtain the minimum porosity and the maximum strength of the lining. These properties are necessary since the lining of this zone is to resist the effect of the melt and melting products;
(b) a lower degree of compaction in the second zone (and a higher porosity);
(c) the lowest degree of compaction in the third zone, i.e. the highest porosity since this zone is to be a buffer one, to provide for compensation of thermal expansion of the lining, and to lower impact effect exerted on said lining in the course of charging the furnace.
To increase the resistance of the lining of the assembly, the lining mass is to be uniformly compacted in the direction of the crucible height.
Moreover, in the course of lining the initial granular composition of the lining mass is to be maintained, i.e. fraction separation thereof must be eliminated.
In this connection it should be noted that the granular composition of the mass and distribution of grains over the volume of the lining mass influence the ratio between the volumes of closed and open pores and the total value of mass porosity, thereby determining numerous properties of the lining, and first of all strength and resistance to the effect of melt. The granular composition of the mass determines the number of contact points between the grains of the refractory material per unit of volume. With the optimum granular composition, voids between coarse grains are filled to the maximum extent with finer grains. The number of contact points and consequently density of the lining mass increase, thereby promoting an increase in the lining resistance.
It should be also noted that in the course of lining the local depletion or enrichment of the lining mass with a binder is to be eliminated.
With all the above requirements being met, the l
REFERENCES:
patent: 3836613 (1974-09-01), Granitzki et al.
Chugunny Evgeny G.
Kucherenko Sergei V.
Shumikhin Vladimir S.
Zemlyavichus Pranas V.
Zhelnis Mechislav V.
Institut Problem Litia Akademii Nauk Ukrainskoi SSR
Kastler S.
Rutledge L. Dewayne
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