SU944722A1 - Liquid self-hardenable mixture for producing casting moulds and cores - Google Patents

Description

(5) LIQUID SELF-DURING MIXTURE FOR THE MANUFACTURE OF CASTING FORMS AND RODS

one

The invention relates to a foundry, namely, liquid self-hardening mixtures (LHS) for the manufacture of casting molds and cores.

Known HSS for the manufacture of casting molds and cores, containing a refractory filler, liquid glass, a dicalcium silicate hardener and water 1.

This mixture has a difficult knockout from castings.

Also known LHS for the manufacture of casting molds and cores, including a refractory filler, liquid glass, a dicalcium silicate hardener, a foaming agent and fuel oil additive to improve embossability 2.

However, fuel oil additives reduce the fluidity of this mixture, which limits the content of fuel oil in the mixture to 0.5-1.0% and does not significantly improve the knockability of mixtures.

In addition, fuel oil is a combustible material, which complicates the storage

CSHC materials.

Closest to the invention in its technical essence and the achieved result is a liquid self-hardening mixture for the manufacture of casting molds and cores, including a refractory filler, liquid glass, a dicalcium silicate hardener, a foaming agent and a technological additive, which is introduced to improve flowability, increase strength and dry

15 condition and facilitate knockout D1.

The technological additive used is sulfate black liquor, which contains sulfur in the amount of 1.73-2.22% of the dry weight of the substance and smelly sulfur-containing compounds: methyl mercapton. dimethyl sulfide dimethyl disulfide, hydrogen sulfide, etc. When heating liquid mixtures with sulphate black liquor, sulfur burns, the amount of bad-smelling volatile compounds age This significantly impairs the sanitary and hygienic working conditions. In addition, sulphate soap is contained in sulphate black liquor, which gradually floats up and separates from the liquor over time, as a result of which the stability of the technological properties of liquid-glass mixtures is disturbed. When soap gets into the mixture, the gas permeability decreases to zero. During the drying of non-gas-permeable or low-permeable mixtures, there are cases of paint peeling, cracking and destruction of forms and cores. Therefore, it is necessary to keep sulphate black liquor for a long time and catch sulphate soap, which complicates the technology of making CSH. Excess foaming of liquid-glass compositions with sulphate black liquor does not ensure high gas permeability of the mixtures. The aim of the invention is to improve the gas permeability and sanitary hygienic working conditions. The goal is achieved by the fact that the liquid self-hardening mixture for the manufacture of casting molds and cores, including a refractory filler, liquid glass, a hardener based on dicalcium silicate foaming agent and technological additive, as a technological additive contains black soda liquor in the following ratio of ingredients, wt.%: Liquid glass 6,83-8,13 Hardener based on dicalcium silicate t ,, 95 Foam breaker 0.08-0.30 Nacre black liquor 0,20-1,50 Refractory filler Rest Nitron black This liquor is black liquid with a brown tint with a density of 1.081, 33 g / cm and a solids content of 15-50%. Unlike sulfate black liquor, soda black liquor contains almost no sulfur compounds. The dry matter of the soda liquor consists on the SO-Z from inorganic and on 6570 from organic substances. Soda black liquor is a waste product in pulp production. The composition of the dry residue of soda black liquor, wt.%: Lignin22,0-28,30 Phenols, fatty and resin acidsY, 08 Hydroxy-acid and Lactones21,22-2,2 Carbonic acid 0.30-0.2 Acetic acid0.37 -0.61 Formic acid, 8-5.0 Sodium, bound organic and inorganic compounds, mi-22.12-2.16 Other compounds Rest of soda black liquor has surface-active properties. With the addition of soda liquor to the liquid composition, the ballast silica glass turns into a binder and gives LSS additional strength. When the content of soda black liquor more than 1.5 weight. gas permeability decreases and hardening slows down, and at a content of less than 0.2 weight L there is no significant relief in the knockout ability of the LSC. For this mixture, preferably using liquid glass with a modulus of 2.8-3.2 and a density of 1.25-1.35 g / cm. The curing agent based on dicalcium silicate can be white self-dissolving slag from ferrochromic production. DS-PAC, KChNR, LSC, Petrova contact, sulfanol, prepared coke-chemical tar, mylonaph and other surfactants that make the mixture fluid can be used as peyoobrazovatel. Enriched quartz sands of class About 1K, - About 2K, About 1K and quartz of class 1K, 2K, 3K and 4K, groups 01, 016, 02 and 0315 can be used as refractory filler. The proposed LCS can be prepared in batch mixers. trbenpepbiBHoro action with paddle or auger mixing organs. The mixture is made as follows. The batch and hardener are loaded into a batch mixer and mixed for 1-2 minutes. The liquid composition was Quartz 1K0287,578 87,578 Ferrochrome slag, 0, 0 Liquid glass of module 3.2 with a density of 1.32, 28 8.13 KCHNR.0.092 0.092 Soda black liquor with a density of 1.23 g / cm 0.05 0.20 Sulfate black liquor with a density of 1.2 g / cm3

Flow cone stroytsnil, mm

Compressive strength, kg / cm, through

1 h 2 h 3 h 110

100

115

1, .6 3.0 3.5 2 in a separate container of liquid glass, soda black liquor and a foaming agent and poured into the mixer after mixing the dry components. After that, the mixture is stirred for another 2-3 minutes and is produced in ready-made form in a snap-in or in an intermediate transfer container. The compositions and properties of the mixtures are given in table. 1 and 2. T a bli c a 1 87.57887.578 87.57887.578 4.0k, Qk, Qk, Q 7.336.83 6.337.33 0.0920.092 0.0920.092 1.001.50 2.00 -.

2it h

After drying

Gas permeability, units, through

1h

I

2h

3h 2h

Work knockout, J, after calcination, Samples disintegrated upon application. As follows id. 2, the addition of soda black liquor improves gas permeability by a factor of two, with a significant improvement in sanitary and hygienic working conditions and maintaining a high level of strength in a dry state and a low work of knockouting of the CSH. The use of this mixture is possible in the production of steel casting any weight. The use of soda black liquor allows to reduce the number of scrap due to lower gas permeability, to increase the productivity of labor during molding and core work.

6.2

5.8

6.3

6.0 8.1 8.0 9.0 10.2

Claims (1)

1. Exchange of experience in the implementation of technical 3-USSR Copyright Certificate The foundry manufacturing technologies No. 529733, cl. B 22 C 1/02, 1975.