RU2086689C1 - Method of treating liquid aluminium alloys - Google Patents

Abstract

FIELD: aluminium alloys. SUBSTANCE: aluminium alloys are refined with 0.2-0.3% liquid fusing agent. Entire volume of alloy and slag is located on metal heel, i.e. primary slag removal does not take place. The thus treated slag is degassed with 0.05-0.06% special pellets under layer of floating slag wetted with liquid fusing agent. EFFECT: improved quality of prepared alloys, reduced loss of aluminium alloys in slags, and sped up treatment procedure. 4 cl, 1 tbl

Description

 The invention relates to metallurgy and foundry, in particular, to methods for refining aluminum alloys.

There is a known method of processing aluminum alloys, according to which a refining flux of 47 KCl, 30 NaCl, 23 Na ₃ AlF _{6 is} poured onto the surface of a liquid alloy, and after its melting, the alloy is treated with hexachloroethane.

 The disadvantages of the known methods are the difficulty of reproducing the method and the low quality of the resulting metal.

 The closest in technical essence and the achieved results is a method of processing liquid aluminum alloys by refining by a separate method in the transfer ladles with a capacity of 500 and 900 kg.

 According to this method, after overflow of an aluminum alloy, slag containing up to 75 aluminum alloy is removed.

At the same time, two Degaser tablets of 78 C ₂ Cl ₆ and 22 NaCl according to TU 6-01-1006-75, immersed with a bell in the bottom of the bucket, degass the alloy in several stages, while the consumption of Degaser is -0.1-0 , 15 in the process of degassing, the bell is moved along the bottom of the bucket.

After degassing is completed, an alloy of 0.5-0.7 liquid flux on the basis of "Preparation MHZ", T 113-08-405-81 of 54.5 NaCl, 32.5 KCl, 13 Na ₂ SiF _{6 is} refined.

 Slag is removed and a coating flux layer is applied to the metal mirror.

 However, the existing processing method does not allow to obtain the required quality of the prepared alloys, in the charge of which, in addition to the primary alloy and first-rate return of own production, secondary aluminum alloys, remelted shavings and slag are added, which leads to increased rejection of cast billets.

 At the same time, due to the initial slag removal, up to 2 aluminum alloys with 1 ton of liquid are dumped.

A long processing time (20 25 min) leads to the cooling of the liquid alloy 50-60 ^o C below the technological and requires significant energy consumption for its heating. In this regard, the known method has a high cost of castings.

 The essence of the invention lies in the fact that in the known method of processing liquid aluminum alloys by refining, the alloy is first processed together with slag by a liquid flux, and then degassed under a layer of the remaining slag and flux and carried out separately in several stages.

 The proposed processing method consists in the fact that at first 0.2 0.3 liquid fluxes are refined on the basis of “Preparation MHZ” according to TU-113-08-405-84 the entire volume of the alloy and slag located on the metal mirror, that is, the initial eat slag.

 Then the alloy is degassed with 0.05 0.06 Degaser tablets, TU 6-01-1006-75 under a layer of floating slag moistened with liquid flux.

 One Degaser tablet is dipped to the bottom with a bell (for a 500 kg bucket) and two bells, one tablet for a 900 kg bucket.

 Due to the tetrachlorethylene leaving the liquid alloy, gas bubbles raise non-metallic inclusions to the surface, which are wetted by liquid flux and coagulated into lumps of slag.

 Due to the created "fluidized bed" with hexachloroethane and due to the combined effect on non-metallic inclusions of liquid flux and "Degaser", more efficient cleaning of the alloy from non-metallic inclusions takes place.

 After the cessation of boiling, the slag is removed from the metal mirror and the alloy is transported to the transfer furnaces.

 Example. The Ak6M2 alloy was processed for casting the "Cylinder Head" 21081 / 21083-1003015 in the transfer bucket with a capacity of 900 kg. For comparison, the processing of the alloy was carried out in a known manner and proposed. Processed several buckets in each way. During processing, samples were poured in order to determine their density and mechanical properties of the initial alloy and refined, slag was removed into a separate container and weighed, the temperature in the crucible of the transfer furnace after distribution and the processing time were controlled. The average data are summarized in the table.

 Using the proposed method for processing liquid aluminum alloys provides, in comparison with known methods, the following advantage. The combined use of refining materials and their introduction into the alloy in the indicated sequence, along with a decrease in their consumption, made it possible to obtain better aluminum alloys with a simultaneous decrease in their losses in slags and a reduction in processing time: it allowed to reduce the rejection of parts in gas sinks; reduce the consumption of email. energy to maintain the process temperature of casting aluminum alloys in the transfer furnaces; unify processing technology; improve working conditions by reducing the emission of refined products into the atmosphere; release part of the equipment; in general, to reduce the workshop cost of casting.

Claims (4)

 1. A method of processing liquid aluminum alloys, including slag removal, degassing, liquid flux refining, settling and re-slag removal, characterized in that prior to slag removal, liquid flux refining is first carried out, and then degassing under a layer of slag and flux with subsequent settling.  2. The method according to claim 1, characterized in that as a liquid flux using a mixture containing, by weight. Sodium Chloride 54.5
Potassium chloride 32.5
Sodium Cremnefluoride 13.0
in the amount of 2 3 kg per 1 ton of molten metal.  3. The method according to claim 1, characterized in that the degassing is carried out with a mixture containing, by weight. Hexachloroethane 78
Sodium Chloride 22
in the form of tablets in an amount of 0.5 to 0.6 kg per 1 ton of molten metal.  4. The method according to claim 1, characterized in that the degassing is carried out simultaneously using two bells by placing one tablet in them.

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