SU1069922A1 - Mix for preparing moulds and cores - Google Patents

Abstract

MIXTURES FOR THE MANUFACTURE OF CASTING FORMS AND RODS, including refractory filler, water glass, water and iron sulfate-based material, which in addition to caustic soda, as a material, improve survivability and simplify the process. on the basis of ferrous sulphate - aqueous ferrous sulphate, for - waste from the production of titanium white, in the following ratio of ingredients, wt.%: Liquid glass 5.0-6.0. Water ferrous sulfate - waste from the production of titanium white. 4-7 Water3-5 Caustic Soda 1.0-1.5 Refractory Filler Else

Description

About O)

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XD ND 0 The invention relates to foundry, namely liquid glass mixtures for the manufacture of casting molds and cores. In the foundry industry, for the manufacture of molds and cores, a wide use has been found of the mixture, in which liquid glass serves as a binder. The known core mixture for the preparation of large iron castings containing,%: quartz sand 90.3, caustic soda 1.7, charcoal pitch 4, liquid glass 4 tl. The disadvantage of liquid-glass mixtures is their difficult knock-out, which is due to the mixture retaining considerable residual strength after casting and the crystallization of the metal in the Form. This reduces labor productivity in the cuttings of the cuttings. Organic or mineral supplements are added to improve blendability. Organic additives, as a rule, are characterized with gas-permeability, which can lead to the formation of defects on the surface of castings. Organic additives / burn out at low temperatures, and at a higher temperature a liquid phase is formed in the mixture and a sintering process takes place. In this case, additives of inorganic origin G2J are more effective. Known molding mixture containing, in wt.%: Silica sand 94.7-97.6, refractory clay-3-5, liquid glass 5-6, 10% sodium hydroxide solution 1-1.5, chalk 0.3 . Chalk is added to improve cleanliness and surface quality. However, this mixture is used only for the manufacture of cast steel, which limits its field of application, has insufficient knockability, since the introduction of clay more than 3% with small amounts of chalk (0.3%) contributes to shifting the maximum strength to higher temperatures { to 1400С), which is very undesirable in obtaining steel castings. In addition, the chalk contained in its composition contributes to the formation of chemical burns. This is due to the fact that during the decomposition of chalk, calcium oxide is released, which, together with aluminum oxide present in clay, and quartz sand, can form a low-melting calcium field-spur that directly affects the formation of a chemical peel on the surface of the casting. Closest to the proposed technical essence and the achieved result is a mixture for the manufacture of casting molds and core, which includes refractory filler, water glass, water and as a material based on iron sulfate by-product when etching steel Sz. The disadvantages of the known mixture is the complexity of the technological process, as it requires to carry out, mixing at temperatures not higher. The vitality of the mixture is very small. With increasing temperature, the rate of hardening increases, which makes it almost impossible to use the mixture at a temperature of 15 ° C. The creation in the working area of low temperatures necessary for the use of the mixture contributes to the deterioration of the working conditions of the workers. In addition, the mixture has unsatisfactory knockability. The purpose of the invention is to improve the knockability, increase survivability and simplify the process. To achieve this goal, the mixture for the manufacture of casting molds and cores, including refractory filler, water glass, water and iron sulfate-based material, additionally contains caustic soda, and as the iron sulfate-based material is aqueous ferrous sulfate, titanium white production waste. , in the following ratio of ingredients, wt.%:; Liquid glass 5.0-6.0. Water ferrous sulfate - waste produced from titanium and white4.0-7.0 Water3-5 Caustic soda1.0-1.5 Refractory filler Else Liquid glass is used as a binder in the mixture. The optimum amount of binder (5-6%) provides the necessary strength properties of the mixture, and an increase leads to the consumption of the binder, and, consequently, to an increase in the cost of the mixture. The aqueous ferrous sulphate is introduced into the mixture as a softening agent, which improves the knockability in the form of titanium white production wastes. This waste is a fine-grained lettuce-colored powder, consisting mainly of aqueous ferrous sulphate — FeSO, nHjC (not less than 96% ) and have the following composition, wt.%: FeSO4, 47.5-54.01 / Fe2 (SOi.) 50.1-3.6, / 45.13-52.5. The fluctuation of the chemical composition within the specified limits of the used waste of the production of titanium whitenes on disintegrating does not have a significant EFFECT. Softening

the effect of the additive - iron sulfate starts to appear already after drying the samples at 150-250 0. This is due to the fact that as a result of the dehydration of iron sulfate, water is removed, which leads to the destruction of the bonds between the grains and thereby causes softening of the mixture. The most intensive separation of water begins at 120-150 ° C. At the same time, up to six water molecules are removed. At 650-750, the iron sulfate begins to decompose with the formation of FeO and release of SOj, which passes through the mixture and breaks the binder film, the bond between the filler grains is broken, and the mixture is further weakened.

Since the effect of the softening agent is effective over a wide range of temperatures, the proposed mixture can be used to make molds and cores in the production of castings from ferrous and non-ferrous metals. . .

The most effective is the content in the mixture of additives of aqueous iron sulfate 4-7%, which is due to the minimum work of knockout. The optimal amount of supplements is 5%. The amount of the additive is less than 4% and more than 7% leads to a deterioration in the knockability of the mixture.

The mixture is moistened with water to improve the packing process.

Breakfast is prepared in runners. He; the refractory filler and aqueous ferrous sulfate are mixed, then water and water are added according to the composition. 10% sodium hydroxide solution. / After adding each next component, stirring is performed for 1-2 minutes. Liquid glass is injected last all at once and mixed for 3-4 minutes.

We use liquid glass with a modulus of 2.78 and a density of 1.410 kg / m.

The mixture is compacted in the usual ways. From the mixture obtained, standard samples of cylindrical shape are prepared with a diameter and height of 50 mm, which are tested for strength, knockability and gas permeability.

For strength, the sample is tested immediately after manufacturing (raw) after exposure to air, dried for 30 minutes at 50-60 C.

Bendability is estimated by the work expended on knocking the cores out of the casting. For this purpose, standard cylindrical specimens of 50x50 mm are installed in sandy-clay molds with a size of -100 and cast with steel and cast iron. The temperature of the molten steel is 15,600, and the iron. After cooling of the metal casting, the knocking of the rods is carried out.

The compositions and properties of the proposed mixtures are given in Tables 1 and 2, respectively.

The survivability of the known mixture is 10 minutes, and the knock-out when the content of ferrous sulfate is 15% 2.0 Ma.% And water glass in the amount of 5.0% by weight is 40-81.

The use of the invention makes it possible to use the mixture when pouring various alloys, simplify the process, improve the knockability of the mixture, use the waste of the chemical industry, expand the raw material base to obtain molding sands by using production wastes, reduces the cost of the mixture and prevents environmental pollution.

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The economic effect from the use of the proposed mixture as compared with the baseline as which the liquid-liquid mixture used in industry was selected, containing, in wt.%: Liquid glass 5.5-6.5, 10% hydrated sodium hydroxide solution 1.0-1, 5, quartz sand the rest will be 400 thousand, rub. by reducing

the complexity of the chopping-knockout works

with the annual production of steel casting 300 thousand tons. Reducing the labor intensity of the chopped-knock-out works, as well as the power consumption, will reduce the cost of pouring tons by 30-35 rubles ..

.In addition, its use will allow solving a number of important social problems: environmental pollution,

the fullest use of production wastes, the release of capital investments made for the organization, construction and maintenance of waste dumps, as well as

expansion of raw materials for foundry.

Table 1

Claims (1)

MIXTURE FOR PRODUCING CASTING FORMS AND RODS, including refractory filler, water glass, water and iron sulfate-based material, characterized in that, in order to improve knockability, increase survivability and simplify the process, it additionally contains caustic soda, and as a material based on iron sulfate - aqueous sulfate jelly ¹ -, for - titanium production waste white, in the following ratio ingredients, wt.%: $ 0-6.0 Liquid glass Aqueous iron sulfate - waste production of titanium white 4-7 Water 3-5 Caustic Soda Refractory 1.0-1.5 § filler Rest Q ' Ml