RU195618U1 - SILICON FILLING STONE - Google Patents

Abstract

The technical solution relates to foundry. The mold contains a casing (1), a heat-insulating layer (5), a lining of refractories (4), cast-iron sides (2) and a working layer (3). The implementation of the working layer of high-alumina refractory concrete prevents the increase in the iron content of the poured silicon, which improves the quality of the ingots. Provides increased service life of the mold. 2 s.p. f-ly, 1 ill.

Description

Technical field

The utility model relates to metallurgy, specifically to equipment for casting silicon and can be used for casting technical silicon, silicon, chromium, manganese ferroalloys.

State of the art

The molten technical silicon obtained in ore-reducing electric furnaces is discharged into a ladle and cast into molds.

Molds are known, which are cast iron castings of a monolithic or composite structure (Snitko Yu.P. et al. “Production of ferrosilicon”, Reference, Novokuznetsk, 2000, pp. 238-241). The disadvantage of these molds is the low operational stability associated with the destruction of the working surface under the influence of high temperatures.

Known cast iron mold (Kokhan L.S. and others. Mechanical equipment of non-ferrous metallurgy plants, M. "Metallurgy", 1988, part 2, p. 256). A disadvantage of a mold of this design is the deterioration of the quality of silicon, since iron is the main undesirable impurity due to the transition of iron from the mold into silicon at the crystallization boundary of silicon, i.e. at the silicon-mold boundary, the iron content in silicon increases, which reduces the consumer properties of silicon.

A known method of producing silicon ingots (patent RU 2077969, B22D 3/00, publ. 04/27/1997). The essence of the invention: on the surface of the hearth of the mold made of coal blocks, periodically, before placing a layer of silicon fines on it, an oxygen-containing boron compound is applied at the surface temperature of the hearth above the melting temperature of this compound, for example boric anhydride, boric acid or borax, not less than than 50-250 ° C, 0.5-5 kg / m ^{2 of} the bottom area. At the same time, the integrity of the lining is maintained for a longer period by preventing the ingot from welding to the hearth and oxidizing the surface of the hearth at high temperatures. The disadvantage of this method is the decrease in the quality of silicon due to the transition of boron to silicon.

A known mold for casting silicon (patent RU 2085324, B22D 3/00, publ. 07/27/1997), including a metal casing and a lining of refractories, partitions located inside the metal casing for the formation between them and the casing of closed cavities filled with powder refractory heat-insulating material, a working layer made of coal blocks. The disadvantage of this mold is the insufficient wear resistance of the working layer and the low life of the mold.

By technical nature, by the presence of common features, this technical solution was adopted as the closest analogue.

Utility Model Disclosure

The technical solution is based on a task aimed at improving the quality of silicon.

The technical result of the proposed solution is to increase the operational stability and service life of the molds while maintaining the quality of the cast silicon.

This goal is achieved in that the working part of the mold, previously made from coal blocks, is made of high-alumina refractory concrete.

Brief Description of the Drawings

In FIG. 1 shows a general view of the mold. The mold consists of a metal casing (1) having the shape of a parallelepiped, cast-iron flanges (2), a working base (3) of high-alumina refractory concrete, refractory masonry made of refractory bricks (4), a heat-insulating layer (5).

Utility Model Implementation

The formation of the working layer is performed as follows: the metal casing (1) of the mold is glued with heat-insulating material to form a heat-insulating layer (5), a refractory brick (4) is laid on the bottom of the casing, cast-iron boards (2) are installed around the perimeter, then a layer of high-alumina heat-resistant concrete of the worker is laid bases (3). The concrete is dried and fired, after which the mold is put into operation. Tests of various grades of heat-resistant concrete.

Example 1. The concrete mixture contained Al ₂ O ₃ 65, wt. % After drying and firing, the mold was operated on a silicon casting for 4 months and was decommissioned due to the destruction of the concrete base.

Example 2. The content of Al ₂ O ₃ in the concrete mixture was 80, wt. % After firing, the mold was in operation on a silicon casting for 6 months, after which the concrete base was destroyed.

Example 3. In the concrete mixture, the content of Al ₂ O ₃ was 85, wt. % The calcined mold was operated for 10 months and was taken out for minor repairs to the base. After restoration of the base, it was operated for 8 months, after this time a complete replacement of the concrete base was required.

Example 4. The content of Al ₂ O ₃ in the concrete mixture was 90, wt. % The operation of the mold before the repair lasted 14 months.

Tests of the mold with a concrete base showed its higher resistance compared to molds made of cast iron. During the tests, the iron content in silicon was monitored. If, when casting silicon into cast-iron molds, the content of iron increased by 0.02-0.04%, which at the border of the variety translated it into a lower category associated with price losses, then when casting silicon into a mold with a concrete base, an increase in the content iron did not occur in silicon, since the cast-iron board of the mold is in the temperature zone where silicon is already crystallizing and there is no interaction between iron and silicon.

The service life of the molds, during testing, with a working surface made of high-alumina refractory concrete with an Al ₂ O ₃ content _of more than 85, wt. % ranged from 10 to 14 months (examples 3-4), while the service life of molds with a working layer made of coal blocks did not exceed 6 months. Low resistance, comparable with molds from coal blocks (6 months), showed molds with concrete content of Al ₂ O ₃ 80, wt. % and less (examples 1-2).

Comparing the existing designs of molds for casting silicon with the proposed technical solution, it should be noted that they have as common features:

- the mold casing is made of a steel sheet in the shape of a parallelepiped;

- the insulating layer is made of refractory bricks;

and the difference from the existing design solutions:

- the working surface of the mold is made of high alumina refractory concrete;

- the side surface of the mold in the form of a frame is made of cast iron.

These differences allow us to conclude that the claimed technical solution meets the criterion of "novelty. The features distinguishing the claimed technical solution from the prototype are not sculpted in other technical solutions and, therefore, provide the claimed solution with the criterion of "inventive step".

Claims (3)

1. A mold for casting silicon, containing a metal casing, a heat-insulating layer, a lining of refractories, a working base and sides, characterized in that the working base is made of high-alumina refractory concrete, and the sides are made of cast iron. 2. The mold according to claim 1, characterized in that the high-alumina concrete contains Al ₂ O ₃ not less than 85 wt. %; 3. The mold according to claim 1 or 2, characterized in that the heat-resistant concrete is dried and fired.

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