RU1838275C - Method for manufacturing refractory articles having inner cavity - Google Patents

Abstract

Usage: the invention relates to a refractory subindustry, in particular to hollow high-alumina and corundum refractories for various industries. Purpose: simplification of manufacturing technology with a reduction in gzzovydeleniyu and reducing the cost of products. SUMMARY OF THE INVENTION: for the manufacture of products, a expanded polystyrene punch with an apparent density of 0.01-0.040 g / cm3 is placed in a mold which is filled with a refractory mass. Then, the raw product with the punch is removed from the mold and dried at 100-150 ° C. At the drying temperature, the styrofoam punch decreases in volume by 2-30 times and is easily removed. After removing the punch, the article is fired. 2 tab.

Description

The invention relates to the refractory industry, namely to high clay; zemny and corundum refractories used as pipelines, as burner blocks or diffusers for heating furnaces of the metallurgical industry, and can be used in the non-ferrous, aviation and other i industries used (Refractory products with internal cavity of simple and complex configuration.

The aim of the invention is to simplify technology while reducing gas emissions and reducing: the cost of hollow refractory products.

This goal is achieved by the fact that in the method of manufacturing refractory products with an internal cavity, including installing a punch-void forming agent into a mold, filling it with a refractory mass, removing a workpiece with a punch from the mold, drying and firing the products, a foam polystyrene punch is used as an emulsifier. with an apparent density of 0.021-0.040 g / cm, while drying is carried out at a temperature of 100-150 ° C, followed by removal of the punch before firing.

Thanks to the proposed material for the punch and the drying mode, the manufacturing technology is greatly simplified by eliminating the operation of burning the thermoplastic bonding of the punch or

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complete burning of the punch in the process

high temperature firing.

With this, gas evolution accompanying the burning of the thermoplastic bond is virtually eliminated;

Styrofoam punches are freely removed from the raw product after drying at 100-150 ° C. decrease in size by 2-30 times.

The apparent density of polystyrene foam punches is 42-87 times lower than the prototype punches, and the cost of I m is 2-35 times lower (see table 1), which leads to a reduction in the cost of finished products,

The proposed method is implemented as follows.

Pmipo / styrene punch with. an apparent density of 0.021-0.40 g / cm1 set i.i (GYPSUM, /V.;pJf: liUiyiO

or metal), fill the mold with a refractory mass, after acquiring the necessary strength, release the raw material with the punch from the mold and place it in a dryer where the maximum temperature of 100-150 ° C is reached. Then, cooling the semi-finished product and removing the punch, the volume of which during the drying of the semi-finished product was reduced by 2-30 times. The semi-finished product freed from the punch is fed for high-temperature firing.

Examples. Punches were made with an average diameter of 55 mm and a height of 60 mm of the composition of the prototype from alumina with thermoplastic bonding and a punch from expanded polystyrene with different apparent densities. These punches were inserted into a metal mold, the mold was assembled with the punch fixed, and the mold was fixed on a vibrating table. A mullitocorundum refractory mass was prepared with a moisture content of about 6% of the following composition, wt.%: Fused corundum fr. 3-0 mm35

mullite fried fr .. mm30

alumina GK vibration-ground

fr. 0.063 mm35

The mass was fed into the gap between the metal shell and the punch fixed in the form. When the mold vibrated, the mass flowed and filled the space between the shell and the punch. After keeping the mass for 30-60 minutes, the mold was disassembled, the raw product was taken out of the mold together with the punch.

The prepared samples with a punch were installed in an oven and heat treated at 100-150 ° С for 2 hours.

When using the prototype punch (from alumina with thermoplastic bonding) in the drying process, the raw refractory

impregnated with a thermoplastic melt

after drying, the punch cannot be removed from the sample and only after

firing after burning out thermoplastic

binding and removal of alumina, i.e. complete removal of the punch, it was possible to carry out high-temperature firing of the product.

Styrofoam punches with an apparent density of 0.047 and 0.057 g / cm3 during this heat treatment destroyed the refractory samples (cracked along the generatrix).

. When using the recommended polystyrene foam punches at an apparent density of 0.017 to 0.040 g / cm3 at temperatures of 100-150 ° C, shrinkage occurred - their volume decreased by 2-30 times and they were easily removed from the raw refractory products. With such a significant change in the volume, the mass of the punches practically does not change (the mass decreased by 0.2-1.4%), which indicates the absence of thermal degradation. Dried samples without foam 5 polyethylene punches were fed to high temperature firing.

The effect of temperature on volumetric measurements of punches with different apparent densities is given in Table 2.

The punches were installed in an oven at a temperature of 70 ° C and after 2 hours of exposure, the temperature was raised to 160 ° C with an interval of 10 ° C and holding for 2 hours at each temperature.

5 The most significant shrinkage at 100-150 ° C are punches with an initial apparent density of pomopolystyrene of 0.01-7-0.040 g / cm3. At a density of 0.047 and 0.057 g / cm, a significant increase is observed.

0 punches ..

This method using polystyrene foam punches with an apparent density of 0.017 to 0.052 g / cm3 was tested in the manufacture of highly complex industrial products - the tee of the reformer and large-sized diffusers. Foam-polystyrene punches were fixed in specially made forms, the forms were attached to a vibrating table and a refractory mass

0 of the above composition was poured by vibration into the mold. Then, the mold with the raw product was fed into the drying chamber, where it was kept at a temperature of 70 ° C for 5-10 hours. After the raw material acquired strength, the mold was disassembled and removed, the temperature in the dryer was raised to 100-150 ° C and the raw material was kept depending on its size from 4 to 24 hours

When using punches with a density of 0,047 and 0,052 raw tee

crumbled, and cracks were observed in the diffuser channels, which is associated with volumetric changes in the punch during thermal treatment, processing,

| When using the punches in the diffuser for the composition of the prototype from alumina with thermoplastic bonding, they could not be removed after heat treatment - the raw product was fired, where the thermoplastic bonding burned out and the alumina was dried out.

| When using punches with an initial apparent density of 0.021 to 0.040 g / cm, the raw product had no defects. Poinsons easily removed products. When using polystyrene foam pans with an apparent density of O, 017 g / cm3, the inner surface of the tee channels and diffusers was somewhat deformed, due to the low strength of the polystyrene foam and its deformation when pouring with a heavy refractory mass (3.1 g / cm) , and also had an unsatisfactory inner surface, which was caused by a poor-quality PU and neon surface due to tearing of individual cells of the polystyrene foam granules and their insufficient sintering due to their maximum foaming.

 The performed experiments and industrial tests showed: 1. When using the punches of the prototype composition, it is impossible to perform the operation of removing the puncheon from the raw material of the product before firing 2. Production of refractory products with an internal cavity using, for example, hollow formers of foam-polystyrene punches with an apparent density of 0.021-0.040 g / cm3, followed by heat treatment at 100-150 ° C and removing the punch before firing, allows you to:

 - significantly simplify the technology and eliminate additional firing on the outcrops

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thermoplastic binding. Burnout of the binder leads to significant gassing and pollution of the atmosphere. For example, when firing 1 punch of a reformer tee made of alumina with a thermoplastic binder weighing 6370 g, 950 g of binder should be removed:

- use significantly lighter polystyrene foam punches, which are 42-87 times lighter than punches of the prototype composition. When using the recommended punches, great physical effort and careful handling are not required to prevent their deformation. For example, the recommended expanded polystyrene punch for a reformer tee weighs 75 g and the alumina punch on a thermoplastic bond of 6370 g;

- reduce the cost of punches by 50 - 87%;

- reduce the consumption of materials for the manufacture of punches by 97.7-98.9%;

- reduce production costs due to the rejection of additional firing 25 by 95%.

Claims (1)

The claims A method of manufacturing refractory articles with an internal cavity, comprising installing a void-forming punch into a mold, filling it with a refractory mass, removing a blank with a punch from the mold, drying and firing, characterized in that, in order to simplify the manufacturing process and reduce gas evolution, So-. in order to reduce the cost of products, polystyrene foam with an apparent density of 0.021-0.040 is used as the material of the blowing agent, drying is carried out at a temperature of 100-150 ° C, followed by removal of the punch before firing. Table 1 35 Continuation of table 1 table 2