JPS6018724B2 - How to dissolve reduced iron - Google Patents

Description

[Detailed Description of the Invention] The present invention improves the melting yield of additives for component adjustment such as recarburizers and the reduced iron itself when melting reduced iron as part of cast iron raw materials in a low frequency induction furnace. The present invention relates to an efficient dissolution method that promotes the reduction reaction of iron oxide in generated slag.

If iron ore is reduced at a relatively low temperature without softening or melting, oxygen is lost from the space occupied by iron oxide, and directly reduced iron (hereinafter referred to as reduced iron) is obtained. The gangue in the ore remains in reduced iron, but there are few impurities derived from gangue and reducing agents in the metallic iron part, and the grade varies depending on the manufacturing method, but it is 80-97% total iron, metallic iron. It is about 70% to spotty%, and the reduction rate (metallic iron/total iron) is about 83% to 96%,
It has great potential as a raw material for key making and cast iron. As mentioned above, this reduced iron contains gangue, etc., so when it is melted together with other materials as a raw material for cast iron, a large amount of slag is generated.Also, reduced iron is a bolus and has a density of 3 to 4. Since the amount per cc is half that of ordinary iron, depending on the melting method, the raw materials are mixed into the slag and it takes a very long time to melt or the melting rate is reduced. Therefore, melting using reduced iron has been carried out in arc furnaces and cupola furnaces, which are relatively easy to deal with these problems. However, in recent years, low-frequency induction furnaces have become widely used as melting furnaces for casting, but one of the advantages of this induction furnace is its large furnace diameter, and for this reason, steel scrap can be used in presses. It is possible to make large quantities of balers formed into large rectangular parallelepipeds. When using this steel scrap as a raw material, additives such as recarburizer, ferrosilicon, and ferromanganese are required to adjust the composition, but the melting yield of these additives is also greatly affected by the slag mentioned above. Therefore, it is desired to establish an efficient melting method when reduced iron is used as part of the raw material for cast iron. In view of the above circumstances, the present invention achieves the intended purpose by the following method.

That is, first, steel scrap and additives for composition adjustment such as carburization and ferrosilicon are added to a low-frequency induction furnace in which a predetermined amount of raw hot water is stored, and the process is carried out while the slag caused by reduced iron is not generated. Dissolve the contents in the bag into the hot water. As a result, the C and Si components of the fallen sun that have melted down can be retained at a high concentration, so the iron oxide in the slag generated during the melting of reduced iron is then reduced to metallic iron with elements such as C and Si. As a result, the amount of slag generated can be expected to be reduced. Next, only reduced iron is charged before the return material. By injecting the reduced iron at a point when the amount of molten metal in the low-frequency induction furnace is relatively small, the molten metal is efficiently concentrated by the induced current, and the reduced iron itself is not mixed into the slag and can be quickly and It can be dissolved with a high yield, and the reduction of the iron oxide described above also proceeds efficiently with this fly oxide. Finally, if fan material is added, the overall dissolution rate will be improved and the reduction of iron oxide in the slag will proceed efficiently. Next, the present invention will be explained with reference to Examples. Example 1 Using a low frequency guided furnace with a melting capacity of 1.5, raw materials were mixed in the following formulation and order.

'1' FC20 cupola source water 500k9 [21 Steel scrap 250k9, recarburizer 19k9, ferrosilicon 14kg, ferromanganese 4.1k9 are poured into the furnace, melted in 20 minutes at a furnace power of 350 to 40 W, and slag off there. .

Fine reduced iron 250k9 Hishiiri, furnace power consumption 130~1
Melts in in 30 minutes with 4 wind MA.

It was observed that the slag effect was sufficient and the reduced iron was rapidly dissolved without being mixed into the slag. '41 return material 5
00k9 bags included.

Electricity is melted for 40 minutes at a furnace body power consumption of 300 to 32 female WA, slag off, and hot water is tapped. The results of operation under the above conditions are shown in Table 1. Reference Example 1 The same materials as in Example 1 were used in the same amounts, but only the order of addition was changed.

Addition order '1) Cupola source water, ■ Reduced iron, [3' Steel scrap 10-ferromanganese + Feo silicon + recarburizing material, '4' Returning village operation results are shown in Table 1.

Reference example 2 The addition order of Reference Example 1 was further changed as follows.

Addition order '11 Cupola source water, ■ Steel scrap, '3} Reduced iron, ■ Ferromanganese + Ferrosilicon +
Table 1 shows the operation results for recarburized material and '5} bunched material.

Table 1 As can be seen from the results of Example 1 and Reference Examples 1 and 2 above, Example 1, which had the same addition order as stated in the claims column, had a higher FeQ reduction in the slag than Reference Examples 1 and 2. The rate is high;
As a result, it can be seen that the amount of slag generated is small, and the dissolution rate of each material is high, making it an efficient melting method.

Claims (1)

[Claims] 1. When melting additives for composition adjustment such as reduced iron, steel scrap, tufting material, and carburizing material as raw materials for cast iron in an induction furnace, steel scrap is first placed in an induction furnace containing the required amount of raw hot water. Reduced iron characterized in that additives for adjusting the composition such as powder and carburizer are charged, reduced iron is charged after the charges have melted down, and finally tassel material is charged. How to dissolve.