SU924116A1 - Method for melting charged blank - Google Patents

Description

The invention relates to ferrous metallurgy, in particular to the smelting of charge blanks in electric arc furnaces.

There is a known method of utilization of dust from steelmaking production, according to which carbon-containing materials are loaded into the arc furnace, and pellets from the dust of steelmaking production are loaded onto this layer and the filling is melted [1].

The disadvantage of this method is the need for sophisticated equipment for the manufacture of pellets from the dust of steelmaking production.

The closest technical solution to the proposed in essence and the achieved positive effect is a method of melting a lightweight metal charge into alloy charge ingots in electric arc furnaces, including batch loading of chips and small fractional metal-abrasive waste of alloyed steels and alloys, fluxing reagent and deoxidizer, 25 melt finishing by temperature; Flux reagent and deoxidizer wastes are mixed in a weight ratio of 1: (0.2-0.5) :( 0.03-0.07) and injected into the furnace in a uniform layer

2

on the surface of the chip together with the last portion of the first filling introduced into the furnace and each subsequent basement in the amount of 15–20% of the total mass of the filled up chips and with the same specific consumption per unit mass of freshly grounded chips, and after melting the entire mass of the charge piled into the furnace : The resulting molten metal is overheated by 60 - 100 ° C above the melting point of the charge and kept at this temperature for 5-10 minutes (2).

However, the known method of smelting charge ingots does not provide a high degree of extraction of alloying elements from waste, a high yield of liquid metal and, consequently, a reduction in the cost of steel produced on them, which is associated with increased waste of chips during the melting period and insufficient deoxidation of the metal after the charge has been melted.

The purpose of the invention is to increase the degree of extraction of alloying elements from waste, the yield of liquid metal in the smelting of the charge of the workpiece and cost reduction you melted on her camp ".

3

924116

four

This goal is achieved by the fact that in the method of smelting the charge stock, including batch loading of chips and small fractional metal-abrasive waste from alloyed steels and alloys, fluxing reagent and deoxidizer, melting the charge and fine-tuning the melt by temperature, lime in an amount of 20-30 kg / t, molybdenum-cobalt catalyst in an amount of 40–80 kg / t, together with coke in a ratio of 1: (6–8), are seated on the furnace hearth, and after the charge is melted, metal is precipitated by deoxidation with a silicon-aluminum alloy. with a ratio of 1: (5-7).

Additive in the filling 20 - 30 kg / t of lime on the one hand provides earlier slag formation, which protects the liquid metal from oxidizing 20 of the furnace atmosphere with oxygen, and on the other hand, contributes to the formation of molten slag with basicity (CaO / HTO) 1.0 - 1.5, reducing the loss of alloying elements 25

(chromium, vanadium, etc.,), both as a result of their lesser oxidation, and as a result of better reduction during deoxidation.

When lime is added to the filling, θ in an amount of less than 20 kg / t, slag is obtained; its basicity of melting is less than 1, which leads to an increase in oxidation of the alloying elements and to the deterioration of the conditions for their reduction from slag. The addition of lime in an amount of more than 30 kg / t to the lime roll significantly increases the amount of slag during the melting period, makes it more difficult to deoxidize and, accordingly, increases the loss of the main alloying elements.

The molybdenum-cobalt catalyst introduced into the composition of the proposed method contains thermodynamically unstable oxides of molybdenum and cobalt, which are easily reduced by carbon already during the melting of the mixture with the release of carbon monoxide _; which significantly reduces the oxidizing potential of the furnace atmo- 5θ sphere and, consequently, the loss of chips and alloying elements. The amount of molybdenum-cobalt catalyst (40-80 kg / t) is calculated in such a way that the reduction reaction 55 continues during the entire melting period of the charge, which increases the efficiency of the proposed smelting method.

With the introduction of filling less than 60

40 kg / t of molybdenum-cobalt catalyst, its amount is insufficient to reduce the oxidizing potential of the furnace atmosphere during the entire period of melting of the charge and leads to an increase in the loss of chips and alloying elements. Additive in the filling more than 80 kg / t molybdenum-cobalt catalyst leads to peroxidation of the bath, which worsens the conditions of its deoxidation and leads to increased losses of the main alloying elements.

After the charge is melted by the proposed method for more fully reducing the alloying elements from slag, a sedimentary deoxidation of the metal is produced with an alloy containing a strong deoxidizing element (aluminum). The ratio of silicon and aluminum in the alloy 1: (5-7) is chosen, in such a way, that aluminum is completely consumed for the deoxidation of the metal, and silicon for the slag and the metal.

I - When the ratio of silicon and aluminum in the alloy is less than 1: 5, all silicon will be spent on metal deoxidation, which leads to an increase in the loss of alloying elements with slag. If the ratio of silicon and aluminum in the alloy to take more than 1: 7, then most of the silicon will go to slag deoxidation, which will lead to a sharp increase in its quantity, reduction of basicity and, accordingly, to an increase in loss of alloying elements, with slag removed from the furnace.

Example. The charge stocking of steel type R6MZ used for smelting high-speed steel is smelted under industrial conditions in a 25-ton electric arc furnace. Lime 25kg / t of molybdenum-cobalt catalyst 60 kg / t together with coke in the ratio of 1: 7 is placed on the hearth of the furnace, and then the basket of high-speed steels shavings is loaded, on top of which are dust-like metal-abrasive wastes of high-speed steels. basement of the second basket with chips. In the process of melting the mixture, immediately after the appearance of a bath of liquid metal, the release of bubbles of carbon monoxide, indicating the reduction of molybdenum and cobalt oxides, is observed, and continued until the end of melting. In the middle of the melting of the mixture is taken for analysis of the sample of furnace gas, in the end - a sample of melting slag. At the end of melting, the metal is purged with oxygen, which is completed after the charge is completely melted, and the metal is precipitated by a silicon-aluminum alloy with a ratio of 1: 6 elements. After soaking for 20 minutes, the metal with a temperature of 1600 C is released into the ladle and poured into 5

924116

6

lower back for ingots weighing 3500 kg. The recorded parameters of the bucket for chemical analysis take a sample of the ^slag and known methods of ^slag are shown in the table.

The gas content in the furnace The content of components and basic The content of components and Output liquid Way noisy atmosphere slag content is smooth news bucket th me smelting re% %, second slag,% Talla,% about ₂ | WITH C _{o rg} about ^! _And oh | & £ Cr ₂ o | ν, ^) ' ---

Known 8.4

Proposed 3.8

2.2 0.3 8.2

1.3 1.2 3.7

21.6 10.8

12.4 14.2 8.2

8.1 1.3 0.1 92

2.0 0.6 1.0 96

The expected economic effect from the introduction of the proposed method of charge blanks into production will be 220 thousand rubles. in year.

Claims (1)

Claim Method of smelting charge billet, including batch loading of chips and small-scale metal-abrasive waste of alloyed steels and alloys, fluxing agent and deoxidizer, melting of the charge and fine-tuning of the melt by temperature, characterized in that, in order to increase the degree of extraction of alloying elements from waste, the output of the liquid metal and reduce the cost of smelted __ steel on it, lime in the amount of 20–30 kg / t, molybdenum-cobalt catalyst in the amount of 40–80 kg / t together with coke in a ratio of 1: (6–8) are placed on the furnace hearth, and after the mixture is melted, sedimentary metal deoxidation with a silicon-aluminum alloy with a ratio of 1: (5-7).