SU1156805A1 - Cold-hardening mixture for making moulds and cores - Google Patents

Abstract

1. COLD MIXTURE FOR THE MANUFACTURE OF CASTING FORMS AND CORES, including a refractory filler based on silica, a material based on iron oxides and a phosphoric acid compound, so as to improve the quality of the forms and rods by increasing their plasticity; as a material based on iron oxides, the mixture contains powdered waste of electric-smelting production containing oxides of alkaline-earth metals, and as a phosphoric acid compound is magnesium aluminum phosphate compound in the form of an aqueous solution of magnesium and aluminum phosphates with a dry matter concentration of 49.5-56, 5 wt.% In the following ratio of ingredients, wt.%: The specified waste steel-melting 1.65-6.50 production Specified magnesium aluminum phosphate 2.0-8.0 compound Refractory filler for Residual silica ove 2. The mixture according to p. 1, I distinguish (O to the fact that this waste of electric-smelting production has the following composition, wt.%: 10-15 Magnesium oxide 4-6 Calcium oxide 11-t3 Alumina Dioxide sl 8 -10 silicon O) 0.5-2.0 Carbon 00 Oxide 6–6 Leza II O Oxide iron lese 111 Else 3. Mixture according to claim 1, characterized by the fact that the specified magnesium alumophosphate compound has the following composition, wt. X: Phosphoric anhydride 40.0-45.0 Magnesium oxide 5.5-6.0 Alumina 4.0-5.5 Water Others

Description

The invention relates to a foundry, namely cold-hardening mixtures for the manufacture of foundry cores and molds.

The disadvantage of mixtures with phosphate bonds is brittleness, which significantly affects the quality of rods of complex configuration, since the removal from the core box causes the formation of spalling and other defects associated with the lack of ductility characteristic of mixtures on resin binders known. self-hardening mixture for the manufacture of casting cores and forms containing: a material based on metal oxides with a valence of 2 (for example, based on magnesium oxide), a concentrated phosphoric acid y, sulfite-yeast mash, and gltserin ogneupor1v second filler C2.

This composition allows to obtain mixtures with a vitality of 8-12 minutes, low flaking ability, strength at the wrapping curing stage of 5-12 kgf / s for stretching. However, the insufficient strength of the rods at the initial stage of curing and the increased brittleness do not exclude the possibility of the formation of cracks in the rods and shapes and the deterioration of their performance properties.

Also known is a mixture for the manufacture of casting molds and cores, containing a binder (50% phosphoric acid and 50% metallurgical dust-production waste in steel smelting in electric arc furnaces) and quartz sand.

This mixture has a vitality of 7-15 minutes, gas permeability 100500 units. and compressive strength after 24 h 18-35 kgf / cm3)

However, the insufficient strength of the mixture at the initial stage of curing, high ostama and brittleness do not allow to obtain high-quality rods.

Closest to the invention to the technical essence and the achieved result is a self-hardening mixture for the manufacture of casting molds and cores, containing, wt.%: Trifolin (containing 62-75%, FeO 25-38%) 4.5-12.0, orthophosphoric 3.5-10 acid, Oh, refractory silica based filler

rest. For a known mixture, vitality, compressive strength and flexural strength 4 are characteristic.

However, the known mixture has a slight deformation during bending in the initial stages of curing, which can lead to the formation of cracks when removing complex rods from the core box.

The aim of the invention is to improve the quality of the forms and cores by increasing their plasticity.

The goal is achieved by the fact that a cold-hardening mixture for the manufacture of casting molds and cores, including a refractory filler based on silica, a material based on iron oxides and a phosphoric acid compound, as a material based on iron oxides, contains a pulverized waste of electric steelmaking with an alkaline-earth oxide content 1X metals, And as a phosphoric acid compound, magnesium aluminum phosphate compound in the form of an aqueous solution of magnesium and aluminum phosphates with a dry concentration Om substance 49,5-56,3 wt in the following ratio of ingredients, wt.%:

Said waste from electro-smelter Melting Production 1, 65-6,50. Mentioned magnesium aluminum phosphate compound 2.0-8.0

Refractory

filler

based

silica remaining

Waste of electrical production has the following chemical composition, wt.%:

Oxide

magni 10-15

Oxide

calcium 4-6

Oxide

aluminum 11-13

Dioxide

silicon 8-10

Carbon 0.5-2.0

Oxide

glands 6-15

Oxide

Iron 111 Remains The magnesium aluminum phosphate compound is an aqueous solution of aluminum and magnesium phosphates and has the following chemical composition, wt%: Phosphoric anhydride 40.0-45.0 mg 5.5-6.0 aluminum. 4.0-5.5 VodaEstalnoe Waste of electric steel-making production is formed when steel is melted in electric arc furnaces, is caught by air filters in the form of dust and is thrown into the dump (approximately 2.5-3.0 thousand tons during smelting 100 thousand tons of steel in year), is a fine dust (specific surface 2500-3500 20 on the instrument PKS-4) with a humidity of 2-5%.

The main difference of the electric steel production is that it contains 14-23% oxides of alkaline earth metals (10-15% magnesium oxide and 4-6% calcium oxide).

The presence of calcium and magnesium oxides leads to an increase in the rate of curing, which allows one to achieve high strength properties in the initial stage of curing and to shorten the holding time of the rods and molds in the tooling. A distinctive feature of the interaction of the magnesium-aluminum phosphate compound with metal oxides, which are part of the electric-smelting production, as compared with orthophosphoric acid, is that the acid reacts more intensively than the magnesium-aluminum phosphate binder and the excessive reaction rate interferes with the normal structure formation. As a result of this interaction with magnesium, the mophosphate compound forms amorphous phases, in contrast to phosphoric acid, which contributes to the formation of crystalline structures that are brittle. Magnesium phosphate compound, belonging to the class of inorganic polymers, is capable of producing structures with increased plasticity. The optimal mass ratio between the magnesium-aluminum phosphate compound and the electroplating content of phosphoric anhydride, magnesium oxide and aluminum oxide, which is greater than suggested, is difficult because of the high viscosity of the solution (more than 250 s for VZ-4), and the lower component content is not gives the desired curing effect when interacting with the waste of an electrostatic production (1.1-1.3): 1. The use of a 1: 1 ratio leads to a decrease in the plasticity and survivability of the mixture, the ratio leads to an increase in the survivability of the mixture and a deterioration in strength at the initial stage of curing. Increasing the content of the magnesium-aluminum phosphate compound and the waste of electric-smelting production in the mixture above the upper limit increases the cost of the mixture, and reducing them above the lower limit cannot be recommended due to the deterioration of the physicomechanical properties, shapes and rods. As refractory filler, distensillimanite, zircon, etc. can be used along with quartz sand. The use of phosphate compounds leplavilnogo production, Example. Magnesium phosphate compound is synthesized as follows. A three-liter, 1-liter round-bottom flask equipped with an oil bath, a stirrer, a reflux condenser, and a thermometer was charged with 375 g of 83% orthophosphoric acid and 30 g of magnesium oxide were dispensed with stirring. Due to the exothermic effect of the reaction, the temperature of the reaction mass rises to 100-110 ° C. After dosing of magnesium oxide, the reaction mass is boiled until the precipitate dissolves. Then stops heating and dispense 32 g of alumina hydrate. After that, the mass is boiled for 1-15 hours at 120-t30c. Cool the reaction mass to 70-80 ° C and add water (63 g) to a constant weight of the reaction mass of 500 g. The product is a Magnesium Phosphate Compound containing phosphoric anhydride 45.02, magnesium oxide 6, OZ, atomic oxide 4.02 water 45.0%. VZ-4 viscosity at 20 С 190-200 s, hydrogen ions index pH 0.5-0.8, density

1.65-1.68 g / cm. In a similar way, AND (a benefit of 335 g of 80% orthophosphoric acid, 28 g of magnesium oxide and 42 g of alumina hydrate are prepared by a magnesium aluminum phosphate compound with a content, in May.%, Of phosphoric ihydride 40.0, magnesium oxide 5.5, alcuminium oxide 5 , 5, water 49.0, viscosity according to VZ-4 at 160-170, the index of hydrogen ions pH 0.6-0.9, density 1.68-1.70 g / cm.

In tab. 1 shows the compositions of the magnesium-phosphate compounds obtained are used to form molding and core mixtures.

Mixtures are prepared as follows. The required amount is introduced into the sand from the electric furnace production and mixing in runners for 2.0-2.5 yins. Then magnesium aluminum phosphate is added. The compound is mixed and mixed for 1.01, 5 minutes, after which standard samples are packed manually or by vibroplates from the resulting mixture; for

tensile and tensile strength tests.

Physico-mechanical parameters are given in table. 2.

From the above data it follows that the proposed mixture has high strengths, the necessary vitality and gas permeability and low ostaemost.

Bending deformation in the initial period (after 0.5 h) is between 0.80-1.25 mm and (after 1 h) is 0.300, 45 mm, which makes it possible to produce rods of complex configuration, known mixtures strain under bending significantly lower - 0.19 mm after 0.5 h and O, 16 mm after 1 h , without breakage And cracking, i.e. contributes to their quality.

Quartz sand 1K0315B

Magnesium phosphate compound (content, wt.%: Phosphoric anhydride 45.0 magnesium oxide 6.0, aluminum oxide 4.0, water 45.0

Magnesium phosphate compound (content, wt.% $ Of phosphoric anhydride 40.0, magnesium oxide 4.5, aluminum oxide 5.5, water 49.0)

Waste of electric steel production

Phosphoric acid

Trifolin

96.35 94.7 93.5 85.5 96.35

2.0 3.0 3.5 8.0

2.0

1.65 2.3 3.0 6.5 1.65

Quartz sand 1K0315V

Magic aluminophosphate compound (content, wt.X: phosphoric anhydride AS, O, magnesium oxide 6.0, aluminum oxide 4.0, water A5.0 Magnesium aluminum phosphate compound (content, cas.X; phosphoric anhydride 40.0, magnesium oxide 4, 5, aluminum oxide 5.5, water 49.0)

Waste of electric steel production

Phosphoric acid

n "k

Trifolin

on a bend, through

0.5 0.9 3.1

3.5

bending

0.80 0.30

8 Continued table. one

I 156805

87.0

93.0 94.5

3,53,5

3,52,0

6.0 7.0

table 2

1,3

3.7

0.5 2.3

6.6 M 3.3 6.4

9.5 6.8

10.0 3.4

1.25 1.10

0.85 0.40 0.35 0.32

Tensile strength, kgf / cm through

Continued table. 2

Claims (1)

1. COLD HARDENING MIXTURE FOR THE PRODUCTION OF CASTING FORMS AND RODS, including a refractory filler. Based on silica, a material based on iron oxides and a phosphoric acid compound, characterized in that, in order to improve the quality of molds and cores by increasing their ductility, the mixture contains the quality of the material based on iron oxides is pulverized waste from electric steelmaking with the content of alkaline earth metal oxides, and the phosphoric acid compound is a magnesium aluminum phosphate compound in the form a solution of magnesium phosphate, and aluminum at a concentration of dry- mu substance 49.5-56.5 may.2 with the following ratio of ingredients, May. 2: Specified waste electrical trostale smelter production 1.65-6.50 Indicated magnial - mophosphate compound 2.0-8.0 Refractory filler on * silica based Rest 2. The mixture according to p. 1, distinguish- u and i with the fact that specified waste electric steel production wa has the following composition, May.2: Magnesium oxide 10-15 Calcium oxide 4-6 Aluminium oxide 11-13 Dioxide silicon 8-10 Carbon 0.5-2.0 Same oxide the forest and 6-15 Same oxide Forest 111 Rest 3. The mixture according to p. 1, distinguish- u and i with the fact that indicated mag niumaluminophosphate the connection has next composition May 2: Phosphoric anhydride 40.0-45.0 Oxide magnesium 5.5-6.0 Oxide aluminum 4.0-5.5 Water Rest SU ... 1156805 '1 1156805 2