CS257700B1 - A method of treating electron-forming molds - Google Patents

Abstract

Treatment of foundry molds and core molds made of mixtures bound with organic binders against the release of harmful fumes during thermal decomposition. After casting, the upper surfaces of the molds are provided with at least one layer of foundry dust containing a 2 to 10% aqueous solution of reagents, such as potassium permanganate or phosphoric acid.

Description

The invention relates to a process for treating foundry molds or core molds made of mixtures bonded with organic binders.

At present, blends bonded with organic binders, especially phenolic, furan, urea, alkyd or combinations thereof, are increasingly being used to produce foundry molds and cores. A large part of these binders releases gaseous products, such as phenols, ammonia, amines, formaldehyde, etc., which are toxic to the human body. In modern foundries, this problem is solved by faithful or less efficient exhaustion or total air exchange, by means of devices which are very expensive. At the same time, the pollutants further contaminate the atmosphere around the foundry, where the exhaust gases are extracted * In older non-mechanized foundries, the effects of these substances in the air are even more pronounced, because all workplaces with pollutant development cannot be exhausted.

These drawbacks are overcome by a method for treating foundry molds or core molds made of organic bonded mixtures according to the inventions, which consists in pouring at least one layer of foundry slag containing 2 to 10% aqueous solution of reagents such as potassium permanganate and / or phosphoric acid *

The process according to the invention is particularly suitable for sites with the highest gas evolution, such as exhausts, around the risers and inlets. The backfill layer is selected according to the mold volume; If the active substances are reacted during the evolution of the pollutants, the powder can be restored. The active substances contained in the powder react with the gaseous pollutants released from the molds. Phenols and formaldehyde are oxidized when aqueous potassium permanganate solution is used. · Diluted phosphoric acid neutralizes ammonia and amines. Mixtures thereof may optionally be used. Common foundry sanding is for example quartz sand, flake, regenerate etc. ·

Example 1

The quartz sand is moistened with a saturated aqueous solution of potassium permanganate to a water content of 6% by volume. The backfill is then applied to the surface of the cast mold containing the phenol-formaldehyde binder.

Example 2

The grit is moistened with a 10% aqueous phosphoric acid solution with a water content of 4% by volume.

Example 3

The mixture is moistened with a mixture of a saturated aqueous solution of potassium permanganate and an aqueous solution of phosphoric acid to a water content of 2% by volume. This backfill is applied to forms containing a urea-formaldehyde binder modified with a phenolic resin.

Claims (1)

SUBJECT OF THE INVENTION Process for treating foundry molds or molds with cores made of organic binder blends, characterized in that, after casting, the top surfaces of the molds are covered by at least one layer of foundry slag containing a 2 to 10% aqueous solution of reagents such as potassium permanganate and / or phosphoric acid. Uzgorodsky Production-Printing Company, Proektnaja 4, Uzhgorod H * 263, Price 2,40 KČs