SU1696496A1 - Method of heating metal scrap - Google Patents

Abstract

The invention relates to methods for heating scrap metal with molten slag and can be used in ferrous and non-ferrous metallurgy. The purpose of the invention is to increase the efficiency of heating scrap and the smelting process. The method includes the steps of entering into the heating capacity of a discrete system of scrap packages, filling the system with slag, holding, removing scrap and solidified slag, separating the system components, using heated packages in a metallurgical furnace. The structure of the system provides for a given ratio of the mass of scrap and slag, the equality of the volume of slag and voids between the packages. When scrap is heated to elevated temperatures, the bag system is poured with slag twice. In the two-stage heating of scrap, the slag in the gap is removed from the heating chamber by a flowable one. J

Description

The invention relates to the production technology of steel, alloys and non-ferrous metals using scrap in the mixture and can be applied in the metallurgical industry.

The purpose of the invention is to increase the efficiency of heating scrap and the smelting process.

The method is carried out as follows.

On the pallet install scrap packages in the form of vertical walls with a calculated gap between them. The pallet is lowered into the heating capacity, which can be used as a slag ladle. The latter is poured molten

slag that completely fills the gaps between scrap packages. The system is maintained until the temperature is at or near equilibrium. At the end of the process, the slag may be in a flowable or crystallized state. The pallet is removed from the heating chamber and the solidified slag is separated from the scrap in a known manner, for example, by vibrating the system. The pallet with partially heated scrap is again placed in the heating chamber and is poured again with molten slag. The final secondary heating temperature may be lower or higher than the slag melting point. After holding the pallet with heat

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The scrap is removed from the heating chamber, the scrap bags are dumped into the tray or the basket and fed into the metallurgical furnace as part of the charge. The slag, after being reheated, is used for the primary heating of the scrap after smelting as described.

Example 1

Single-stage heating of scrap by the final slag of converter smelting.

Initial data for calculation: the initial temperature of the converter slag is 1600 ° C; final slag temperature 1150 ° С; the initial scrap temperature is 20 ° C; the final scrap temperature is 1160 ° С. Heat capacity: US 0,624 kcal / kg.grad; US 0,463 kcal / kg.grad; sЈ 0.105 kcal / kg.grad; C "0.163 kcal / kg.grad.

Scrap density in packages is 3120 kg / m 1, molten slag density is 2910 kg / m.

The heat of the slag is qlu (ct) ur (ct) ui 465.95 kcal / kg.

The heat required to heat scrap pp (ct) Hct) fl 185.35 kcal / kg.

The mass ratio of scrap - slag Kq 2.51 kg / kg.

The volume ratio of scrap - slag Kv 2.34 m3 / m3.

The structure of the scrap on the pallet when the thickness of the packages, for example, 400 mm spread with a gap of 400 / 2.34 170.0 mm.

The dwell time depends on the porosity of the packages, their thickness and the set heating temperatures of the scrap, it is 40-90 minutes. After aging, the pallet is removed, vibratory oscillations destroy the bond of the slag with the scrap and serve the latter at 1150 ° C to the converter.

Example 2. Two-stage heating of scrap converter slag to 1350 ° C. Since the structure of scrap in both heating periods remains unchanged, the intermediate heating temperature of scrap is

under the terms of Kq1 Kq2.

1-stage heating. The disposable heat of slag dS1 208.65 kcal kg. Heat perceived by scrap is accepted followed by refinement (t ni 933 ° C), for i 69.42 kcal / kg. The mass ratio of scrap - slag Kqi 3,00 kg / kg.

And the heating stage, the disposable heat of slag is more than 440.85 kcal / kg.

The heat perceived by the dL2 scrap is 147.18 kcal / kg. The mass ratio of scrap - slag KCH2 2.99 kg / kg,

Due to the good convergence of Kq, the calculation is not repeated.

The volume ratio of scrap - slag Kv 2,79 m3 / m5.

The thickness of the packages is 400 mm, then the gap between the vertical walls is set at 143 mm.

From a comparison of options 1 and 2, it can be seen that

in the 2nd version, scrap was reported as a result of 645.5 kcal / kg of heat, which is 183.55 kcal / kg more than in variant 1, however, slag consumption is reduced by 7%.

When used in the metal charge

50% of the scrap slag yield in the converter is 175 kg / ton of scrap, i.e. Ka 5.71. So c), cc) the slag-to-metal converter does not correspond to the conditions of examples 1 and 2 and it is necessary to involve slags for heating scrap

non-converting redistribution, for example, house-. According to calculations at a factory with a complete metallurgical cycle, it is necessary to use 31.4% of blast furnace slag for these purposes to heat converter converter scrap, which consumes all the produced iron.

It follows from the calculation that when the scrap fraction in the metal charge is up to 50% and when converter slag is used for heating, the yield of which is 15% by weight of steel, the ratio of slag to scrap is 0.9. The same calculation with respect to the blast furnace slag gives a value of 1.8. According to the proposed method, the scrap is heated by slag, therefore the total heat consumption is reduced.

Thus, by the duration of the process in the converter and by the cost of heat, the proposed method provides greater efficiency.

Technologically, the heating of scrap metal with slag is also more beneficial: metal oxidation does not occur; the scrap is at the end of the process covered with frozen slag (or part of the slag),

This protects the packages, especially lightweight, from. waste in the converter; Lightweight packages are filled with slag and from the inside, and contact heating with slag is an order of magnitude more intense than heating with gas.

Claims (1)

Invention Formula The method of heating scrap metal in the smelting of steel, alloys and nonferrous megaliths, including the introduction of scrap into the tank, filling the porosities in it with molten slag, holding and removing slag, characterized in that, in order to increase the efficiency of scrap heating, slag is introduced into packaged scrap at a mass ratio of scrap and slag equal to 1: (0.9-1.8), while the volume of slag is equal to the volume of voids between the packages and inside the packages.