SU1346323A1 - Self-hardening sand for making moulds - Google Patents

Abstract

The invention relates to a foundry industry, namely, to compositions of self-hardening cement mixtures for the manufacture of casting molds (F), mostly larger ones. The purpose of the invention is to improve the quality of F by increasing their strength at all stages of curing and reducing friability While maintaining the required vitality of the mixture, as well as improved 11 knockout F. The composition of the mixture, wt.%: Liquid technical lignosulfonate 2.2 ... 3.0 ; water 2.5 ... 3.4; calcium fluoroaluminate clinker 3.7 ... 5.3; refractory material based on silica - the rest, and the clinker has the following composition, wt.%: Cao 45 ... 52; A1HO43.5 ... 47.9; Si02l, 5 ... 2.5; , 2 ... 0.8; 0.3 .., 0.7; 0.2 ... 0.5; F 2.3 ... 2.6 and the following modular characteristics: lime binding coefficient KS .0.89. ..0.99; silicate1 module p 0.03 ... 0.05; alumina (aluminate) module p 59.,. 218. Due to the use of clinker of the indicated composition while maintaining a high survivability of the mixture (55-60 minutes), which is necessary according to the conditions of the manufacturing technology of large forms, the strength indicators at all stages of curing are increased B 1.5-2 times, crumbling reduced by 4-5 times, significantly improved knockability (to reduce the residual strength). 3 tab. UD (L with 4 05 00 ГчЭ СО

Description

The invention relates to a foundry, namely, molding sands with mineral binders for obtaining high-quality castings with regard to environmental requirements.

The purpose of the invention is to improve the quality of the forms by increasing their strength at all stages of curing and reducing the crumbling rate while maintaining the mixture survivability indices, which are technologically necessary for the preparation of large forms, as well as improving the dislodgeability of the forms.

The lime binding coefficient — the CS coefficient, which takes into account the incomplete saturation of acid oxides (SiO, AljOj,) with calcium oxide in the process of calcining raw materials, is calculated using the formula j5 (, ...

1.87 SiO;, - t-0.94 Al-jOj 1.4, 54 F

With an increase in KS, the hydration reaction accelerates, the strength of the bound structure increases. The proposed mixture provides for the use of clinker with a COP of 0.99 - 0.89.

Silicate modulus n characterizes the ratio of the silicate phase and the total content of aluminate and alumoferritic phases in clinker

;

AljOj + B VdOz

With a decrease in n, clinker sets and hardens faster. The proposed mixture provides for the use of clinker with p 0.03 - 0.05.

Alumina (aluminate) modulus p characterizes the ratio and composition of aluminate and ashomoferritic phases in clinker

., D Pe.Oz-

A clinker with a high p-value seizes and hardens faster. Clinker cp 59-218 is used in the mix.

The use of clinker with the specified indicators of the feast is due to the requirements for its reactivity (hydration) capacity and the blending of raw materials when it is produced at the cement plant.

The clinker is the product of solid phase sintering of the raw mix at

P

 followed by grinding the product to a finely divided state (specific surface 0.5-0.6). As components of the raw mix, various compounds of aluminum and calcium can be used, for example, garnet slimes of alumina production.

In tab. 1 shows the compositions of mixtures 1-3.

 The compositions of the clinkers used in the compositions of mixtures 1-3 are given in table 2.

The test results of mixtures 1-3 are given in table 3.

Due to the use of the specified composition in the composition of the proposed clinker mixture, the strength characteristics of the mixtures are 1.5-2 times at all stages of curing, the crumbling rate is reduced by 4-5 times, the knockability is significantly improved (to reduce the residual strength). At the same time, the vitality of the mixtures maintains high rates (55-60 minutes), technologically necessary for the preparation of large and especially large forms,

P-rmula of the invention

A self-hardening mixture for the manufacture of casting molds is predominantly large, containing silica-based refractory material, liquid technical lignosulfonate, water and hydraulic in a calcium aluminate content, which, in order to improve the quality of the forms, increase their durability to all During the stages of curing and lowering the precipitability while maintaining the required survivability of the mixture, as well as improving the moldability, the mixture as a hydraulic binder contains a calcium fluoride luminate clinker. Qi in the following ratio of ingredients, wt.%:

Liquid technical lignosulphonate 2.2 - 3.0 Water2.5 - 3.4

. Clinker on the basis of calcium fluoride-aluminate 3.7-5.3 Refractory material on the basis of silica Else In this case, the clinker based on calcium fluoride-aluminate has the following composition, in mass%:

Calcium Oxide Alumina Silicon Oxide Iron Trioxide Sodium Oxide Potassium Oxide Fluorine

1346323

45.0-52.0 and following modular characteristics:

43.5 - 47.9 1.5 - 2.5 0.2 - 0.8 5 0.3 - 0.7 0.2 - 0.5 0.3 - 2.6

Coefficient of contact for lime, KS

0,89 - 0,99 Silicate module, p 0.03-0.05

Alumina (aluminate) module, p59-218

Calcium fluoroaluminate clinker 3.7

Refractory based material

silica

150.0 44.5 2.0 0.4 0.4 0.3 2.40.98 0.4 89

249,8 44,6 2,2 0,3 0,3 0,3 0,3 2,50,99 0,05 149

3.47,5 46,7 2,3 0,3 0,3 0,3 0,3 2,60-, 99 0,05 156

Coefficient of contact for lime, KS

0,89 - 0,99 Silicate module, p 0.03-0.05

Alumina (aluminate) module, p59-218

, 5 90.1

5.3 88.3

table 2

Vitality, min

Compressive strength, kgf / cm, through, h:

1 3 6 8

24 Dropsiness,%, after 24 h

Residual compressive strength, kgf / cm, after warming up to temperature, С:

Compiled by S.Teplov Tehred A. Kravchuk

Circulation 741

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5

Production and printing company, Uzhgorod, st. Project, 4

Table 3

55

60

60

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Claims (1)

Claim A self-hardening mixture for the manufacture of predominantly large foundry molds containing silica-based refractory material, liquid technical lignosulfonate, water and a hydraulic binder containing calcium aluminates, characterized in that, in order to improve the quality of the molds by increasing their strength at all stages of curing and lowering crumbling while maintaining the required survivability of the mixture, as well as improving the knockability of forms, the mixture as a hydraulic binder contains a clinker based on calcium fluoroaluminate In the following ratio of ingredients, wt.%: Liquid technical lignosulfonate 2.2-3.0 Water 2.5-3.4. · Clinker based on calcium fluoroaluminate 3.7-5.3 Silica-based refractory material Moreover, clinker. Based on calcium fluoroaluminate has the following composition, wt.%: 3 1346323 4 Calcium oxide 45.0 - 52.0 and The following modular characteristics: Aluminium oxide 43.5 - 47.9 Binding coefficient Silica 1,5 - 2,5 lime, cop 0.89 - 0.99 Iron trioxide 0.2 - 0.8 ₅ 1 Sodium oxide 0.3 - 0.7 Silicate module, η 0.03 - 0.05 Potassium oxide 0.2 - 0.5 Alumina (aluminate - Fluorine 0.3 - 2.6 nd) module, p 59 - 218 Table 1 Ingredients Content, wt. in mixtures 1 ³ Liquid technical lignosulfonate 2.2 3.0 Water 2,5 2.7 ’ 3.4 Calcium fluoroaluminate clinker 3,7 4,5 5.3 Silica-based refractory material 91.6 90.1 88.3 I table 2 Compositions of molding mixtures CaO The content of ingredients (oxides) in clinker, wt.% ACO, SiOg ^Re ₂ ° 3 Ma ₂ Oh to _r about F ” The cop L R 1 50,0 44.5 2.0 0.4 0.4 0.3 2,4 0.98 0.4 89 2 49.8 44.6 2.2 oh s oh s 0.3 2,5 0.99 0.05 149 3. 47.5 46.7 2,3 0.3 oh s 0.3 2.6 0-, 99 0.05 156 Table 3 Properties Performance indicators for mixtures ’[ ² ] 3 Vitality, min 55 60 60 Compressive strength, kgf / cm ² , through, h: 1 oz 0.4 0.4 3 2 3 3 6 4 8 6 8 12 12· 12 24 20 20 20 Shedding,%, after 24 hours 0.06 0,07 0,07 Residual compressive strength, kgf / cm®, after warming up to Peratures * C: 400 3 4 4 800 ’ 0.1 0.1 oz