SU1435365A1 - Self-hardening sand for making moulds and cores - Google Patents

Abstract

The invention relates to foundry and can be used to make casting molds and rods from self-hardening liquid mixtures. The purpose of the invention is to increase the strength of the mixture and improve its knockability, which is achieved by introducing white soot into the composition of the mixture - waste of aluminum fluoride production. The mixture contains, wt%: liquid glass 5.0 ... 7.0; soap stock of alkaline refining of vegetable oil O, 23 ... O, 27; white soot - waste production of aluminum fluoride 1.5 ... 2.5; water 2.0 ... 3.0; quartz sand else. The introduction of white soot contributes to the homogeneity of the binder film on the surface of the sand grains, thereby increasing the strength. In addition, the introduction of white soot contributes to the improvement of the module of liquid glass and improve the bleedability of the mixture. 3 tab. (Oh (L

Description

four:

co 00 00) ate

The invention relates to foundry and can be used to make casting molds and cores from self-hardening liquid mixtures.

The purpose of the invention is to increase the strength of the mixture and improve its knock-out.

The mixture contains a refractory filler j binder, a surfactant, a hardener and water.

In the composition of LSC, molding sand is used as a refractory filler, as well as surfactant soap stock of alkaline refining of vegetable oil, binder is liquid glass. White soot is used as a hardener as a waste product for the production of aluminum fluoride.

Bela soot has physico-chemical indicators, which are listed in Table. one.

Table 1

Appearance Fine powder white color

2.0

W; about 5.0

80.0 70.0 60.0

4.0

3-7

4.5 5.0

4-12 7-15

0.3 5-7

0.5 1.0

4-7

4-7

Continuation of table 1

ten

)five

20

25

thirty

35

40

45

50

55

Nasypna

density,

g / l, not

more than 270 350 400

Granulometric composition - residue on a sieve 0045 mm,%, not more than 10 10 10,

Bela soot is obtained as a by-product of the production of aluminum fluoride by the interaction of hydrofluoric acid cream with aluminum hydroxide and the subsequent separation of silicon from aluminum fluoride solution:

Н251Рб + 2А1 (ОН) з - 2А1Рз + 4Н ,, 0 + siO.

and has the formula

SiOi -Al Oj

The physical density of white soot is 2.0-2.1 t / m. Bela soot in water is insoluble. The surface area is 50.

The preparation of the mixture is carried out in batch mixers for LSS batch or continuous operation as follows.

First, in a paddle mixer with continuous action, two compositions of liquid components are prepared: the first liquid composition — liquid glass with soap stock — the second liquid composition — white carbon black with water. Then, molding sand is loaded into the included GSS mixer and the calculated amount of liquid compositions is simultaneously pumped through the pipelines. The dosage of the liquid composition is carried out according to the relay, time. Mixing time is 0.5-1.0 min. The finished mixture is discharged into a core box or dispenser.

When mixing liquid glass, soap stock, white soot and water a homogeneous solution is formed, not subject to delamination. This ensures that the binder film is homogeneous on the surface of the sand grains after the mixture is cured, which results in the expansion of the initial flow mixture.

As an impurity, aluminum fluoride is a part of white soot. When aluminum fluoride interacts with liquid glass, sodium oxide is formed:

Zyuz NajO - NZO

2A1Rz +

  + + HjSiF. Sodium oxide interacts with fine SiOj (specific surface 50) contained in white soot to form liquid glass;

SiO,

+

 SiO-j-NajO +.

Thus, white soot, taking sodium oxide from the liquid glass introduced into the mixture, increases the modulus of the liquid glass during the mixture hardening process, as a result, the sintering of the mixture sharply decreases when the metal is poured and the embossability is improved. The release of the .j is even more conducive to improving the mixability of the mixture.

The compositions of the mixtures are given in table 2, their technological properties - in table. 3

Tabliya2

Table 3

Initial humidity,%, not more than

Gas permeability of dry samples, units, 5, not less

Compressive strength, MPa, not less: 0 after 1 h

after 3 h

Vitality, 5 min, not less

Cone flow, mm, not less

4.0

120

5.0 6.0

120

120

0.15 0.45

10 165

0.20 0.50

10 170

0.25 0.55

ten

175

0.25 .0.30 0.35

0, 23 0.25 0.27

0

five

0

The data given in table. 3, show that the proposed mixture has, as compared with the known, 2-3 times higher strength and 3-5 times less knockout work.

The mixture can be used in a mechanized and automated method of making molds.

Claims (1)

Invention Formula The self-hardening mixture for the manufacture of casting molds and cores, containing quartz sand, water glass, cauldron of alkaline refining of vegetable oil, a hardener and water, is different in that it is used as a hardener 1А35365 -To contains white soot - waste oil production 0.23-0.27 fluoride aluminum with the following Bela Soot - waste the overall ratio of ingredients, May.%: production of liquid liquid glass 5-7. aluminum aluminum 1.5-2.5 Soap stock alkaline Water2-3 refining ras-quartz sand Else