SU1247149A1 - Composition for making foundry moulds and cores - Google Patents

Description

Invention; relates to foundry and can be used to make molds and cores from self-hardening liquid mixtures.

The purpose of the invention is to increase the strength of the mixture after curing. The mixture contains refractory nap

frother, partially neutralized black liquor and water,

Quartz, zirconium, olivine and other sands are used as refractory fillers. Liquid glass according to GOST 13079-81 or liquid glass prepared from siliceous sedimentary rocks is used in the mixture. The specific weight of liquid glass is 1.31-1.35 g / cm, silicate module 2.5-3.4. Compounds based on two-calcium silicate, for example, ferrochromic slag (TU 14-11-95 -74) or nepheline sludge (STU-30-748-64), as a frother - sulfonol DS-PAC, RAS, KCHNR, mylonafta, Petrov contact and other surfactants.

Partially neutralized black liquor (LCH) is prepared by neutralizing black liquor with organic (acetic, formic, oxalic) or mineral (hydrochloric, sulfuric, phosphoric) acids. Black liquor is a by-product of soda or sulphate pulping for the preparation of low-frequency boilers. The density of black liquor 1.20-1.37 g / cm, the solids content of 25-50%,

Neutralization of the black liquor is carried out in an apparatus with a mixer by supplying it with acid, continuously measuring the pH of the pH to pH 7.8-10.3. The product obtained immediately after preparation can be used to prepare the mixture, the LFs is a colloidal solution of lignin in acid form. Fatty and resinous acids, hydroxy acids, phenols in LSPs are in free form and not in the form of sodium salts, which takes place in black liquor, therefore the introduction of LSPs in a fluid-mobile mixture contributes to the transition of liquid glass to a gel state, B present. In the presence of small amounts of hardener, a chain reaction of the polymerization of silicic acids occurs with the most complete transformation into polysilicon

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acid, providing strength mixtures. When black liquor is neutralized to a pH below 7.8, liquid glass is rapidly coagulated, the strength and vitality of the mixtures decrease, and the pH of the liquor does not reach 9.8.

The mixture is prepared as follows.

 In the mixer, a liquid composition is prepared containing liquid glass, low-frequency water and a foaming agent, and poured into runners pre-filled with refractory filler, mixing. The mixture is boiled for 2-3 minutes and a hardener is introduced into the mixture through a dosing device, mixed for 1 minute and the mixture is discharged to fill the molds and core boxes.

In tab. 1 shows the proposed (1-10) and limestone (11) compositions of HCS, in table. 2 - the physicomechanical properties of these mixtures.

As follows from the table. 2, the strength of the proposed mixtures is 40% or more superior than the strength of the known.

, When the content of LSPs is less than 0.4%, the strength decreases, and when the content of LCPs is more than 1%, the mixture survivability, mixtures with LSPs with pH less than 7.8 (mixture 1) have low vitality and strength, and at pH 10, 3 (mixture 10) - insufficient strength. The most optimal is a mixture of 6.

When the content of liquid glass is less than 5.8 wt.%, The strength decreases after curing, and an increase in its amount of more than 7.0 wt.% Is undesirable, since this increases the knockability of mixtures. When the hardener content is less than 2.0 wt.%, The duration of solidification increases, and its increase is more

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5.0 wt.% Leads to rapid setting of mixtures.

The content of the foaming agent less than 0.08 wt.% Does not allow to transfer the mixture to a liquid-mobile state, and if its amount exceeds 0.3 wt.%, The duration of the mixture hardening increases

The use of the invention in the production conditions allows to increase the strength of liquid-fluid mixtures after their solidification and to reduce the scrap of castings.

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Claims (2)

MIXTURE FOR THE PRODUCTION OF CASTING FORMS AND RODS, including a refractory filler based on silicon dioxide, liquid glass, a foaming agent, a product for processing wood into cellulose and a hardener, characterized in that, in order to increase the strength of the mixture after curing, as a processing product wood in cellulose, it contains black liquor neutralized with organic or mineral acid to a pH of 7.8-10.3 and additionally water with the following ingredients, wt.%: Liquid glass Hardener Foaming agent Neutralized with organic or mineral acid up to pH 7.8-10.3 black liquor Water Refractory in relation 5.8-7.0 2.0-5.0 0.08-0.30 0.4-1.0 0.4-2.2 tel. Based on silica The rest is _aa SU ..J247149 A1 . 1 12