SU897871A1 - Method of metallic scrap preparation for smelting - Google Patents

Description

one

The invention relates to non-ferrous metallurgy and, in particular, to techno; of metal scrap preparation for smelting.

The closest technical

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The essence is a method of preparing scrap metal for smelting, including heating it, mechanically separating the resulting carbon and chemical removal of the tin coating 13.

However, the method is rather complicated, since the heating is carried out in a non-oxidizing atmosphere, and the coating is removed in the molten salt.

The aim of the invention is to simplify the technology.

The goal is achieved by the fact that according to the method of preparing scrap metal for smelting, including heating of the scrap, the mechanical separation of the obtained carbon and chemical removal of the tin coating, after mechanical separation of the carbon, the scrap is cooled to C, and the coating is removed to 40-70 ° C. 10-20% solution of caustic soda for min, then the scrap is washed in water and calcined at 150-300C.

Heating (firing) of piston scrap should be carried out at 00–490 ° C for 1030 minutes, since at lower temperatures full carbon deposits do not occur, and at

At temperatures above, there is a danger of the pistons melting. After firing, the pistons are cooled to for the subsequent removal of tin from the surface of the pistons.

15

The verification of the developed firing modes shows the complete removal of oil and traces of carbonization from the pistons, which indicates their optimality.

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Claims (1)

In order to remove tin from the burned pistons, it is proposed to wash it off chemically in an aqueous solution of alkali NaOH. The maximum degree of flushing of olov from the pistons is provided with an alkali concentration within 102Q% with an etching time of 5-15 minutes and at a solution temperature of 40-70 ° C. The use of solutions with a higher concentration is undesirable, since there is an intensive dissolution of the base of the piston and the loss of aluminum. Treatment is recommended under optimal conditions in caustic soda solution for 10 minutes. Heating the solution to {O-PP contributes to the acceleration and more complete washout of tin from the surface of the pistons. Rinsing In water and calcination at 150,300 ° C, it is performed to prevent oxidation of the pistons during storage and to prevent saturation of the melt with hydrogen that would have occurred when raw pistons were used in the mixture. The method is carried out as follows. Scrap pistons, such as AK 12 MMGN alloys, are received for processing. AK 12 K2 MgN, AK21M 2, 5H 2.5, polluted with oil, carbon, tin, iron attachments. The contaminated scrap is fed to a furnace, where it is heated at a temperature of kQQ-kSQ ° C for 1030 minutes. With such an extract, a coke-separating sediment is formed on the surface of the pistons, which is easily separated by shaking. The most suitable furnaces for burning scrap are continuous type furnaces used for heat treatment of castings, or powder metallurgy furnaces, but chamber type furnaces with scrap loading into the furnace can be used in troughs. From the furnace, a scrap of pistons is fed to a vibrating table with openings, where the resulting pistons are separated, and after cooling to C, the pistons are sorted by alloy grades. The sorting is done by marking existing on the pistons or on the standards of the respective brands of pistons. The pistons are folded into the box with holes. In the boxes, the pistons come in a chemical washout, which is produced with a concentration of 1020 in caustic soda solution, heated to 4070С. Flushing time min depending on the temperature of the solution and standard pistons. The boxes are then removed from the solution and fed 4 for washing in water. After washing in water, the pistons are fed to the drying chambers. The scrap dried at 150-300C is fed to the installation for crushing pistons and separating iron attachments. It is also possible to use a specialized continuous baking unit for firing and subsequent washing of the pistons. In this case, the pistons are sorted according to the standards before firing. At the plant for crushing and separating iron accessories, pistons are supplied by alloy grades. The crushed piston scrap enters the conveying furnace and after unloading from the furnace through the conveyor system enters the washing chamber with a solution of caustic soda, then with water and is fed into the drying chambers. Dried crushed scrap is supplied in boxes to the smelting furnaces. Scrap pistons from alloy AK21M2.5 H2.5 are calcined at 50 ° C for 15 minutes, after which the resulting separation of the resulting carbon is carried out and then cooled to 25 ° C. The cooled pistons arrive at a chemical washout of the tinned layer, which is carried out in a 15% caustic soda solution heated to 50 ° C for 5 minutes. The scrap thus treated contained less than 0.01 tin. The proposed method provides scrap cleaning from oil, carbon deposits and complete removal of tin from the surface of the pistons, which makes it possible to use piston scrap in the smelting of heat-resistant piston alloys. In addition, the scrap processing process is simplified, since there is no need to prepare molten salts. The use in the charge in the preparation of heat-resistant piston aluminum alloys, the total amount of the formed cushioning scrap of these alloys, allows saving expensive and scarce primary metals. The invention of the method of preparing scrap metal for smelting, including heating it, the mechanical separation of the resulting carbon and chemical removal sl-o5 897871 in this coating, differs - 15 min, then the scrap is washed in water and | q and with the fact that, with the aim of easier-calcined at 150-300 C. nor technology, after mechanical deposits of scrap are cooled to sources of information, ZO-AOC, stripping coatings are taken into account when examining heated to 0-70 C 10-20 -N1. UK patent caustic soda solution for 1299P8, cl. Since 70 1972.