CS207140B1 - Self-hardening ferrochrome,by the slag hardened modelling mixture for making the foundry moulds and cores - Google Patents

Description

The present invention relates to a self-setting ferro-chromium slag-curable pattern composition for the production of foundry molds and cores comprising asphaltic materials and waterglass.

In the production of foundry molds and cores, to a large extent, self-setting mixtures are used, in which water glass is used as a binder. The mixtures are then cured with either solid or liquid hardeners. The grinding materials used for these known self-setting mixtures must not have a higher content of leachable substances, while the content of other fractions with a grain size of less than 0.1 mm also causes difficulties. Therefore, for the preparation of these hitherto known self-setting mixtures, mostly new, high purity grit materials are used. Regeneration of these mixtures is currently unresolved and recovery costs, including installation costs, are high.

The situation is even more unfavorable now, because from the economic point of view, the model self-setting water-bonded mixture and the bentonite filling mixture appear to be the most economical for mold making. It is difficult to regenerate mixtures with these two binder systems, while achieving a correspondingly higher percentage of these regenerates in the mixture.

The purpose of the invention is to provide such a self-curing, ferro-chrome slag-curable, model mix for the production of foundry molds and cores, for which recyclable non-regenerated sand with a higher content of leachable materials is utilized as much as possible.

The present invention is based on a self-setting ferro-chromium slag curable model mix for the production of foundry molds and cores, consisting of 15 to 65 parts by weight of non-regenerated sand, which is already used for foundry purposes, containing 5 to 20% leachable substances. 3.5% active bituminous residues with a softening point of at least 55 ° C, and from 8 to 27 parts by weight of new quartz sand grit, the model mixture is complemented by 5 to 8 parts by weight of water glass with a density of 42 ° to 48 ° Bé , 5 to 3.

The advanced model for the self-curing, ferro-chromium slag-curable, model mixture according to the invention is first and foremost that it is utilized to a large extent by the return of non-regenerated sand and hence the regeneration is completely eliminated in the production of the self-curing mixture. The active asphalt content of the return non-regenerated sand is sufficient for this mixture with said relatively high leachable content to have the same values of workability, strength and abrasion as the mixture processed only from new grinding materials.

The self-setting model mix according to the invention for the production of foundry molds and cores is made up of 15 to 65 parts by weight of non-reclaimed sand, 8 to 27 parts by weight of new quartz sand grit and 8 to 27 parts by weight of water glass. 5 to 3. Returnable non-regenerated, that is already used for foundry purposes, the sand contains according to its original purpose varying proportions of leachable substances and residues of asphaltic admixtures. For the purposes of the present invention, it is desirable that the leachable content be in the range of 5 to 20% and the content of still active asphaltic residues with a softening point of at least 55 ° C is 0.5 to 3.5%. The self-curing of the self-setting model mixture is carried out as usual by the addition of 0.5 to 3.5% ferro-chromium slag, the amount of addition being controlled by the required or workable pot life.

One example of an operationally suitable composition of a self-setting model composition of the invention is characterized by the following composition:

unrecoverable returnable 45 wt. parts sand new quartz sand 55 wt. parts sharp water glass 42 ° to

48 ° Bé, modulus 2.5 to 3.6 masses, parts ferochrome slag 0.5 to 3.5%

This self-setting model mix has the necessary and usual basic properties of compounds for foundry purposes, that is breathability binding to raw moisture

200-400 Si j 8-25kPa 4-5.5% and in the exemplary embodiment according to the invention it has the following physical properties: workability of the mixture without ferochrome slag within 26 hours workability of the mixture with ferochrome slag up to 30 min abrasion after 24 h 2 mm

The model composition of the invention naturally varies with time and its strength values are shown in the following table.

time in min 30 60 120 240 24 h strength in kPa 250 500 650 800 1000

The self-setting model mix containing 15 to 65 parts by weight of non-regenerated sand retains the above properties required for foundry production throughout this range. However, above the proportion of 65 parts by weight of the return non-regenerated sand in the content of the self-setting model mixture, its properties change sharply, ie it falls below the necessary technical values. With a content of less than 15 parts by weight, the self-setting model mix almost assumes the composition of the mix made of new quartz sand grit, and its technical and economic benefits are reduced to virtually negligible levels.

Claims (1)

OBJECT OF THE INVENTION Self-setting ,. ferro-chromium slag-hardened model mix for the production of foundry molds and cores containing asphaltic substances and water glass, processed from recycled sand and new sanding, characterized in that it consists of 15 to 65 parts by weight of unrecovered recycled sand, that is already used for foundry purposes, containing 5 to 20% washable substances, 0.5 to 3.5% active bituminous residues with a softening point of at least 55 °, and from 8 to 27 parts by weight of new quartz sand grit, the model mixture is supplemented with 5 to 8 parts by weight of waterglass of density 42 ° to 48 ° Being a module of 2.5 to 3.