SU1764759A1 - Mixture for casting molds and cores - Google Patents

Abstract

Use: The invention relates to foundry and can be used for the manufacture of casting molds and cores from self-hardening liquid-glass mixtures, mainly under conditions of individual and small-scale production. The essence of the invention: the mixture contains, wt%: liquid glass 2.5 ... 3.0; dust-like waste from the filters of the sites for preparation of iron and chromite ore powders, coke, fireclay and ferrosilicon 1.5 ... 3.0; refractory filler - the rest. Introduction of dust-like waste from filters containing oxides of iron, magnesium, calcium to the mixture reduces the internal energy of liquid glass, which causes a decrease in energy at the interface of the refractory filler - liquid glass, which leads to an improvement in the mixture of casting from the castings. In addition, the presence of silicon-containing material in the dust-like waste ensures self-solidification of the mixture. 1 hp ff, 3 tab.

Description

with

WITH

The invention relates to the field of foundry, and more specifically to liquid-crystal self-hardening mixtures for the manufacture of foundry molds and cores under conditions of individual and small-scale production.

Known self-hardening mixture for the manufacture of casting molds and cores, containing, wt.%: Liquid glass 5.0-7.0, boiler dust 2.5-3.6, water 1.8-2.2, refractory filler - the rest.

The disadvantages of this mixture are: the high content of liquid glass in the mixture, the low strength of the mixture and the content in the boiler dust of toxic material - fluorine. ;,

A self-hardening mixture is also known, in which dust from electrostatic precipitators of cement factories is used as a hardener. Mixture has the following

composition of components, wt.%: liquid glass 6-7, dust from electrostatic precipitators of cement plants 0.5-1.0, the refractory filler - the rest. The high content of liquid glass in this mixture reduces the knockability of this mixture.

The closest in technical essence is a mixture containing a refractory filler, liquid glass and a technological additive — a powdered silica-containing alloy (powdered ferrosilicon with a particle size of 3-4 µm) and petroleum pitch.

The disadvantage of this mixture is that conditioned ground ferrosilicon is used as a hardener, which impairs its knockability, regenerability, and significantly increases the cost of the mixture.

The purpose of the invention is to improve the release of the mixture, increase its vitality and

vi o vi e o o

gas permeability, as well as a decrease in precipitability and cost.

The proposed mixture contains refractory filler, liquid glass and technological additive. As a technological additive, the mixture contains dust-like waste from the filters of the areas for preparation of iron and chromite ore powders, coke, chamotte and ferrosilicon powder in the following ratio of ingredients, wt.%:

Liquid glass2-3-3.0

Dust waste from site filters

powder preparation

forks of iron chromite ore, coke, fireclay and ferrosilicon 1.5-3.0 Refractory filler Rest Dusty waste has the following composition, wt.%:

Carbon31,56-33,5

Silicon25.2-26.1

Calcium oxides 1.9-2.1

Magnesium oxides 0.5-0.6

Chromium oxides3,4-3,8

Sulfur0.03-0.04

Iron oxidesEverything else

The reduced content (2.5-3.0%) of liquid glass in the proposed mixture is the most effective way to facilitate knockout.

If the content of liquid glass is less than 2.5%, C02 blowing or heat drying will be required to obtain the required technological strength, and this will increase the labor costs for the manufacture of casting molds and cores, crumbling, the shelf life of the molds and cores will decrease. When the content of liquid glass is more than 3%, the knock-out deteriorates.

Use as a technological additive dusty waste containing mainly carbonaceous material, contributing to the absorption of molten liquid glass, provides an improvement in the knockability of the mixture.

Oxides of iron, magnesium, and calcium contained in wastes also contribute to the improvement in knock-out, due to the reduction of energy at the interface of the refractory filler - liquid glass. The silicon-containing material contained in the waste ensures the self-hardening of the mixture.

With the introduction of dust waste less than 1.5%, the rate of solidification of the mixture slows down and the strength of the mixture decreases, and more than 3% decreases

the durability of the mixture and decreases the compressive strength during long-term storage (day), shedding increases.

In addition, the use of dust-like wastes that were previously dumped into the dump, allows to reduce the cost of the mixture, to reduce the number of components of the mixture, which simplifies the process of preparation of the mixture and increases the stability of properties.

The mixture is prepared in mixing runners in the following sequence.

Runners are loaded with a calculated amount of refractory filler and pulverized waste, mixed for 1.5 minutes, added liquid glass and stirred for another 3 minutes.

Quartz sand, zircon, and distylene-sillimanite are used as refractory materials.

Dusty waste from the filters of the sites for preparation of iron and chromite ore powders, coke, fireclay and ferrosilicon powders is formed during the transportation of dried materials, their crushing and sieving. 70-80% of this dust has a fraction of 10-60 microns. The chemical composition of the dust waste is medium static by sampling over the course of the year.

To confirm the optimality of the composition, mixtures were prepared for the manufacture of casting molds and cores, the contents of which are listed in Table 1.

Compositions 1, 2, 3 have the proposed ratio of components, and compositions 4 and 5 have a content of components beyond the boundary values of the proposed mixture using quartz sand as a refractory filler. Compositions 6 and 7 have the proposed ratio of components and disthene as a refractory filler -sillimanite, compounds 8 and 9 - the proposed ratio of components and as a refractory filler zircon. Composition 10 - the composition of the prototype.

For the preparation of mixtures, the contents of the components of which are given in Table 1, powdered waste was used, having the composition of components, wt% (see Table 2).

Liquid glass was used with a modulus of 2-2.5 and a density of 1.46-1.48 g / cm3.

Table 3 shows the averaged indicators of the physicomechanical and technological properties of the proposed mixture and the properties of the prototype mixture.

From the data of Table 3 it follows that the proposed mixture has a higher

knockout, tenacity, gas permeability, lower frittability. All this contributes to improving the quality of castings. In addition, the use of pulverized waste reduces the cost of the mixture.

Claims (2)

Claim 1. Mixture for the manufacture of casting molds and cores, mainly in the manufacture of casting in conditions of individual and small-scale production, including a refractory filler, water glass and technological additive, characterized in that, in order to improve the blendability of the mixture, increase its vitality and gas permeability, as well as reducing the precipitability and cost, it as a technological additive contains dust-like waste from the filters of the areas of preparation of iron and chromite ore powders, coke chamotte - 2.5-3.0; and ferrosilicon in the following ratio of ingredients, wt.%: liquid glass dust-like waste from site filters preparation of powders of iron and chromite ore, chamotte coke and ferrosolite refractory filler 2. The mixture according to claim 1, wherein the pulverulent waste has the following 5 chemical composition, wt.%: carbon-31.56-33.5; silicon-25.2-26.1; calcium oxide - 1.9-2.1; magnesium oxide - 0.5-0.6; 0 oxides of chromium-3,4-3,8; sulfur - 0.03-0.04; iron oxides - the rest. Table 1 -1.5-3.0 - the rest. table 2 Table 3