SU1685585A1 - Casting mould and core sand - Google Patents

Abstract

The invention relates to a foundry and can be used to make casting molds and cores from carbon dioxide-cured liquid-glass mixtures. The purpose of the invention is to increase the strength of the mixture, improving its knockability and reducing the consumption of silica sand. The mixture contains, wt.% Liquid glass 6.0-7.0 and regenerate neutralized with caustic soda, obtained from the waste sand-resin mixture by a dry mechanical method with loss on ignition, equal to 0.8-3.2%. The introduction of the regenerate into the mixture makes it possible to introduce additional organic matter into the mixture in the form of a film evenly distributed over the surface of the regenerate sand grains and thereby increase the adhesive strength of the mixture. In addition, the high content of organics improves the knockability of the mixture. 3 tab. (L

Description

The invention relates to a foundry and can be used to make casting molds and cores from carbon dioxide-cured liquid-glass mixtures.

The purpose of the invention is to increase the strength of the mixture, improving its knockability and reducing the consumption of silica sand.

The mixture contains a binder and a refractory filler.

The binder is water glass. A regenerate is used as a refractory filler, which is obtained from a spent sand-resin mixture by a dry mechanical method with loss on ignition (ppp) 0.8–3.2%.

Use in the composition of the mixture as a refractory filler regenerated with caustic soda with rec. 0.8-3.2% obtained from the spent sand-resin mixture by a dry mechanical method, allows increasing the content in the mixture of organic additives, which contribute to an improvement in the sintering quality of the mixture compared to the prototype while simultaneously increasing the strength of the properties of the mixture and reducing consumption of fresh sand in its preparation.

In contrast to the known mixture, additional organic material is introduced into the proposed mixture not in the form of a powdered technological additive, but in the form of a film evenly distributed over the surface of the regenerate grains of sand, as a result of which the increase in the content of organic BOSOOS SL

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substances in the mixture is not accompanied by a drop in its strength properties. The fall in the strength properties of the mixture is also prevented by neutralization of acid residues in the regenerate with caustic soda.

Regenerate has a smaller specific surface area compared to fresh sand, which contributes to improving the strength properties of the mixture.

The increased content of organic substances in the mixture allows more complete destruction of liquid glass during the process of heating the mixture and destruction of the binder regenerate film and reduce the adhesion of liquid glass to the surface of the sand grains in the region of sintering temperatures of the mixture (800 ° C), which improves the blendability of the mixture.

The regenerate sand-resin mixture is obtained at a pilot installation of mechanical regeneration of the design of the Central Research Institute of Metallurgical Technology.

Sand-resin mixture, subject to regeneration, has the following composition, wt.%;

Quartz sand 92.5

Urea formaldehyde resin KF-90 5,0

Phosphoric acid 2.5

A FORM is prepared from a mixture of this composition, which is poured with 35L steel at 1580 ° C in a metal: form ratio of 1: 9. After pouring, the form is knocked out, and the pieces of the mixture are crushed to the size of sand grains. the ground mixture is 3.7%. Subjecting this mixture of mechanical regeneration at different durations of treatment, a regenerate is obtained with a different content ppp: 3.2; 2.1; 0.8; 0.63%.

The chemical composition of the regenerated sand with PPP.21.% Is given in table.1.

Brand of the regenerated sand KO16A.

The titre of the regenerate sand-resin mixture with 10% NaOH solution, found that in order to neutralize orthophosphoric acid residues in 1000 g of regenerate, 35 ml of 10% aqueous NaOH solution is required. The set amount of NaOH is introduced into the mixture while stirring the regenerate in the runners. Further preparation of the mixture is carried out in the usual way. Liquid glass was added to the runners and the mixture was stirred for 2 minutes.

When testing standard specimens, molded from the prepared mixture, the crushability, tensile strength after C02 purge and the knockout performance of standard specimens after their heating at 200, 400, 600, 800 and 900 ° C are determined.

The compositions of the proposed mixtures are given in table 2, the results of their tests in table 3.

As can be seen from the above data in Table 3, the mixture containing the regenerate with PP.0.8-3.2%, has a sufficiently high strength after purging with carbon dioxide and low work of knocking out.

Claims (1)

Invention Formula The mixture for the manufacture of casting molds and cores, cured by carbon dioxide, contains liquid glass and refractory filler, which, in order to increase the strength of the mixture, improve its knockout ™ and reduce the consumption of quartz sand, it contains neutral - regenerated listed with caustic soda, obtained from the spent sand-resin mixture by a dry mechanical method with loss on ignition equal to 0.8–3.2%, with the following ratio of ingredients, wt.%: Liquid glass6-7 Regenerate with the mentioned properties of the rest Table Table Table