CZ2006701A3 - Out-of-furnace metallurgical treatment of cast iron melt - Google Patents

Abstract

Non-furnace metallurgical processing of the cast iron melt takes place in the foundry ladle (1), wherein the foundry ladle (1) is provided with a nozzle (3) for supplying oxygen gas (4) to the cast iron melt (2). In the exothermic reaction of oxygen with silicon, carbon and phosphorus, the melt is mixed with an inert gas (8) e.g. with argon, which is injected into the melt of cast iron (2) through a porous perforated liner (7) in the foundry ladle (1), while simultaneously exhausting the flue gas (11). the melt of the cast iron (2) to desulfurize the melt with magnesium, wherein the speed of movement of the profiled wire (12) is controlled.

Description

Non-furnace metallurgical processing of cast iron melt.

Technical field.

The invention refers to a process for producing spheroidal graphite cast iron from a liquid batch melted in a conventional metallurgical aggregate.

Molten liquid charge - cast iron melt is metallurgically processed in a ladle using heat obtained by oxidation of elements contained in the melt with gaseous oxygen such as silicon, manganese and possibly other elements. The required oxygen is injected into the liquid metal surface by a special nozzle.

The heat obtained by oxidation of silicon and other elements allows metallurgical treatment of the liquid metal associated with the consumption of heat such as alloying, carburizing and desulfurization of the cast iron melt.

BACKGROUND OF THE INVENTION.

The production of ductile iron castings began in 1948 and since then, more than 74 ductile iron castings have been known. All ductile iron production methods are based on modifying the ductile iron melt with pure magnesium or its alloys with metallic elements in a ladle or in a special device (converter). The melt is also desulfurized in this way. Both the modification and desulphurisation significantly reduce the temperature of the melt. This reduction in melt temperature limits the scope and duration of the reactions.

Depending on the nature of the technical equipment used, the use of the magnesium modifying element changes while the temperature of the modified melt is lowered and the air pollution around the production equipment is changing.

The success of these processes for producing ductile cast iron is dependent on ensuring that the melt of the cast iron is mixed with magnesium and thus the reactions between the modifier and the cast iron melt.

In order to make better use of the magnesium modifying element, great care is taken to avoid contact of cast iron and the modifying element with air oxygen.

The essence of the technical solution

The above-mentioned drawbacks are eliminated by the out-of-furnace metallurgical treatment of cast iron melt in a foundry ladle, characterized in that the foundry ladle is equipped with a nozzle for supplying gaseous oxygen to the cast iron melt. an inert gas such as argon, which is injected into the cast iron melt through a porous perforated liner in a foundry ladle while exhausting the flue gas by a not shown apparatus, and further comprising a device for moving the section wire into the cast iron melt to desulfurize the melt with magnesium; profile wire is adjustable. Furthermore, in the foundry ladle, it is possible to raise the melt temperature by oxidizing elements having a higher affinity for oxygen than iron by blowing oxygen gas onto the surface of the cast iron melt. It is possible to modify the chemical composition of the cast iron melt by alloying to increase the content of the desired elements, and further that in the foundry ladle, the chemical composition of the cast iron melt can be adjusted by reducing the content of elements having a higher affinity for oxygen than iron.

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-2Overview of figures in drawings

The solution of the apparatus is shown in Fig. 1, which shows a cross-section of a foundry ladle for off-furnace metallurgical processing of cast iron melt.

Exemplary embodiment

An example of the device is a foundry ladle for the out-of-furnace metallurgical processing of cast iron melt, which was melted in any furnace aggregate, preferably in a cupola furnace, where gray cast iron is normally produced. The necessary chemical composition of the cast iron melt intended for off-furnace processing is carried out by changing the batch components dosed into the cupola furnace. The cast iron melt is poured from the cupola furnace through a tap hole into a transport pan, previously dried and heated. To avoid oxidation of the melt, a suitable carburizing agent is added. A precisely weighed amount of cast iron melt is poured from a transport ladle into a foundry ladle 11, adapted for off-furnace metallurgical treatment of cast iron melt 2. The off-furnace cast iron melt 2 consists of burning silicon in cast iron melt 2 with oxygen gas 4 blown to the cast iron melt level. 2 while stirring the melt of cast iron 2 with an inert gas 8, e.g. The heat generated by the exothermic reaction heats the melt of cast iron 2 while decreasing the silicon content of the melt of cast iron 2. Increasing the temperature of the melt 2 allows metallurgical operations such as alloying, carburizing, etc. Before performing metallurgical operations, slag withdrawal is desirable. After the metallurgical treatment has been completed and the desired chemical composition of the melt has been achieved, desulfurization is carried out using a profile wire 12 which contains, for example, a magnesium-silicon alloy and possibly rare elements. The feed rate 13 of the profile wire 12 is adjustable and is selected so that its end is melted at the bottom of the ladle F At the same time as the magnesium alloys are dosed, the cast iron melt is stirred by a stream of inert gas 8, eg argon. The foundry ladle 1 is provided with an outlet 10 for exhausting the flue gas 11 with a device (not shown). The functional parts of the device are cooled in the foundry ladle 1 by the water supplied in pipes 6 and 9.

Depending on the nature of the metallurgical process, it is also possible to modify the desulfurized melt of cast iron 2 after the slag has been withdrawn in the foundry mold 1. Further, a single-stage desulfurization and modification with a profile wire 12 is possible.

An example of the equipment provided is also the necessary specification of metallurgical processing values. The cast iron melt is poured from the cupola through a tap hole into a transport pan, previously dried and heated to a temperature of 600 to 800 ° C, to avoid oxidation of the melt, a suitable carburizer is added to the bottom of the transport pan. A certain amount of suitable carbohydrate is added to the surface of the cast iron melt to prevent oxidaea. Desirably, the temperature of the liquid melt in the transfer pan is in the range of 1400 to 1420 ° C. A precisely weighed amount of cast iron melt is poured from a transport ladle into a foundry ladle adapted for off-furnace metallurgical processing of the cast iron melt. Alloys are added to the foundry ladle in the required amount for the initial chemical composition, which is shown in Table 1 of Sample No. 2/1, when the temperature of the melt reached 1371 ° C, when it was stirred with argon and when the gaseous oxygen was blown for 3 min. After sampling for sample 2/2, the melt temperature was 1435 ° C and this represents a temperature increase of 64 ° C. The temperature of 1400 ° C was reached after the metal stood and the slag was withdrawn, followed by further heating of the melt. By washing with argon and blowing oxygen gas to the melt surface for 2 min, a final melt temperature of 1451 ° C was reached, which represents a temperature increase of 51 ° C. The chemical composition of the melt is given according to sample no. 2/3. After the slag was stripped off, the profile wire was desulfurized with a length of 40 meters of M21109 alloy while washing with argon. The chemical composition of the desulfurized melt is shown in Sample No. 2/4. The melt temperature after desulfurization was 1370 ° C. The process of off-furnace cast iron melt processing was carried out while reducing the weight of the melt from the original 1352 kg to the final 1280 kg.

Modification of cast iron melt was performed by the in-mold method using the modification alloy Elmag 5800 in the amount of 8.8 kg. The final composition of the ductile iron is shown in Sample No. 2/5.

Tab.č.l. Change of temperature and chemical composition of the melt

Sample no. C% Si% Mn% % WITH% Cu% Ni% Mg% Temperature ° C 2/1 3.68 2.50 0.12 0,044 0,047 0.29 0.21 0.0 1371 2/2 3.64 2.25 0.11 0,044 0.050 0.30 0.21 0.0 1435 2/3 3.68 2.08 0.10 0.050 0.050 0.29 0.21 0.0 1451 2/4 *. 3.70 2.22 0.10 0,045 0.012 0.29 0.21 0.02 1370 *** 2/5 ** 3.62 2.84 0.08 0,044 0.005 0.33 0.21 0,067

* Sample after desulfurization ** Sample after desulfurization and modification * * * Casting temperature

Industrial applicability

The technical effect lies in the out-of-furnace metallurgical treatment of cast iron melt in a foundry ladle for the production of ductile iron castings by influencing the chemical composition of the cast iron, increasing the temperature, alloying, desulfurization and modification of the cast iron melt at higher process productivity and lower costs without using additional metallurgical aggregates.

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Claims (5)

PATENT CLAIMS Out-of-furnace metallurgical treatment of cast iron melt in a foundry ladle, characterized in that the foundry ladle (1) is provided with a nozzle (3) for supplying oxygen gas (4) to the cast iron melt (2), the melt being an exothermic reaction of oxygen with silicon; mixed with an inert gas (8), eg argon, which is injected into the melt of cast iron (2) through a porous perforated liner (7) in a foundry ladle (1), while exhausting the flue gas (11) by a device (not shown). Out-of-furnace metallurgical treatment of cast iron melt in a foundry ladle according to claim 1, characterized in that the foundry ladle (1) is provided with a device for moving the section wire (12) into the cast iron melt (2) to desulfurize the melt with magnesium. (12) is adjustable. Out-of-furnace metallurgical treatment of cast iron melt in a foundry ladle according to claim (1) and according to claim (2), characterized in that in the foundry ladle (1) the melt temperature (2) can be increased by oxidizing elements having a higher affinity to oxygen than iron, by injecting oxygen gas (4) onto the cast iron melt surface (2). Out-of-furnace metallurgical treatment of cast iron melt in a foundry ladle according to claim 1 and claim 2, characterized in that the chemical composition of the cast iron melt (2) can be modified by alloying in the foundry ladle (2) to increase the content of the desired elements. Out-of-furnace metallurgical treatment of cast iron melt in a foundry ladle according to claim 1 and claim 2, characterized in that in the foundry ladle (1) the chemical composition of the cast iron melt (2) can be modified by reducing the content of elements having higher affinity to oxygen than iron.