JPS6260813A - Continuous refining method - Google Patents

Abstract

PURPOSE:To continuously refine a high Cr alloy steel, etc., at a good yield with less electric power consumption by connecting a melt reduction furnace and decarburization furnace and continuously introducing molten metal to the decarburization furnace while adding molten iron subjected to a preliminary treatment to the molten metal after the reduction reaction. CONSTITUTION:Chromium ore, carboneous material, etc., are supplied from the top of the melt reduction furnace 1 through a lance 2. Oxygen is blown from a lance 3 and oxygen and Ar, etc., are blown from a lower tuyere 4 to effect the melt reduction reaction. The molten high-carbon ferrochromium steel with which the reaction ends is tapped from the furnace and is introduced into the decarburization furnace 7 while the molten iron subjected to the preliminary treatment is added to said steel. Oxygen is supplied from an upper lance 8 into the decarburization furnace 7 and the oxygen and Ar, etc., are blown up from a lower tuyere 9 to effect the decarburization reaction. The molten steel treated to have the carbon at the lower ratio is fed to a pit 13 for component adjustment and is subjected to component adjustment.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to producing metals or alloys, particularly high chromium alloy steels such as stainless steel, with extremely low carbon content, at low cost, and with high yield. The present invention relates to a continuous refining method.

[Conventional technology]

Various types of iron manufacturing methods have been proposed for use in the iron manufacturing industry.

Specifically, there are methods known as the Dored method, the ELRED method, the INRED method, the COIN method, the KR method, the Kawasaki Steel method, and the Sumitomo Metal method.

In addition to these conventional measures, as part of resource saving measures,
Collaborative research and development as a national project has begun on this type of steelmaking technology, and the results are gradually beginning to appear.

All of these methods have their own characteristics, and the refining methods that accompany them naturally come in various forms, each with its own characteristics.

For example, ferrochrome molten metal obtained by reducing fil Ts electric furnace ore is solidified and used as a chromium source when producing stainless steel as a ferroalloy; (2) adding carbon and flux to chromium ore; There is a method in which the ferrochrome molten metal obtained by supplying oxygen is solidified and used as a ferroalloy as a chromium source when manufacturing stainless steel, and (3) a separate stainless steel manufacturing process in which the ferrochrome molten metal obtained by reducing ore in an electric furnace is directly used. or (4) add chromium ore to hot metal and while supplying oxygen, add carbonaceous material and flux to produce chromium-compatible metal,
There are methods such as decarburization and adjustment of chromium I content after that.

In addition to these smelting methods, conventional high chromium alloy steels, such as stainless steel, are produced by heating, melting, and reducing chromium ore in an electric furnace. Generally, it was manufactured through a process of melting and refining it in an electric furnace or converter furnace along with other iron sources such as scrap and hot metal.

[Problem that the invention seeks to solve]

However, these techniques have latent or actual problems as described below.

First, since the use of an electric furnace requires a huge amount of electricity, it is not necessarily advantageous from an economical point of view, and there has been a desire to establish a more economical method. Furthermore, it is disadvantageous from an energy standpoint to produce chromium alloy steel by solidifying a chromium source as a ferroalloy and then melting it with other iron sources.

Furthermore, melting of crude stainless steel melt or crude high carbon ferrochrome melt in a conventional electric furnace or converter, smelting process, e.g., melting of ferrochrome by reduction of chromium ore, melting of ferrochrome alloy iron and other iron sources, chromium-containing In processing and carrying out decarburization of crude molten metal, a batch method is adopted for grains, and a large-capacity furnace is required according to the production volume.

For example, in the case of the above-mentioned national project, a processing method is adopted in which about 3 tons of molten metal containing about 60% chromium is processed in a top-bottom blowing converter of about 15 mm in size.

This is because molten metal is made while supplying carbonaceous materials, but because gangue is mixed in with the ore, for example, to produce 1 ton of molten metal containing about 60% chromium, about 1 ton of slag is added. live.

However, since the density of this material is about 1/3, its volume becomes enormous, and this is the reason why a large-capacity furnace is required.

[Means for solving problems]

The present invention is based on the idea that it would be advantageous to directly reduce ore to produce a chromium source using inexpensive carbonaceous materials as an energy source without using electricity. As a result of various studies on scouring technology for crude molten metal, we connected a smelting reduction furnace and a decarburization furnace, and in the smelting reduction furnace, oxygen gas was supplied from a lance, and oxygen and nitrogen or While one or more gases of argon gas are injected, a flux of ore, carbonaceous material, lime, etc. is supplied together with these gases or alone to cause a reduction reaction, and pre-treated hot metal is added to the molten metal sent from there. This is a continuous process in which the decarburization reaction and component adjustment are carried out by continuously leading the carbon to the decarburization furnace, where oxygen is blown from the lance, and argon, nitrogen, and oxygen are blown from the tuyere at the bottom of the furnace. The refining method has been achieved.

[For production]

Hereinafter, the configuration of the present invention will be explained in more detail using the drawings.

The drawing shows an example of the apparatus used when carrying out the present invention. First, from the upper part of the melting reduction furnace 1, for example,
Chromium ore and carbonaceous materials are supplied through the raw material supply lance 2, and oxygen is blown in through a separate lance 3.Otherwise, oxygen and argon are blown in through the tuyere 4 at the bottom of the furnace to initiate the melting and reduction reaction. This process produces high carbon ferrochrome molten metal.

The upper part of the melting reduction furnace 1 has an input port 5 for separately inputting scrap, chromium ore, carbonaceous material, and flux, and also has an exhaust port 6 for degassing.

In this melting reduction furnace 1, the reduction reaction proceeds continuously, and the high-carbon 7-erochrome molten metal is tapped out one after another after the reaction has been completed.

The molten metal is then led to the decarburization furnace 7, but prior to its introduction, pretreated hot metal is added to the decarburization furnace 7.

In this decarburization furnace 7, oxygen is supplied by a lance 8 extending from above, and oxygen and argon for dilution are blown up from a tuyere 9 at the bottom of the furnace.

Note that this decarburization furnace 7 is also equipped with an exhaust port 9 for generated gas.

Note that, as a matter of course, the pretreated hot metal can also be continuously charged into the smelting reduction furnace.

In this case, instead of high carbon ferrochrome, a component corresponding to crude stainless steel melt rJ5 with a low chromium concentration is continuously discharged.

In addition, if degassing is necessary, it is also possible to equip the decarburizing furnace or the component adjustment pit with a vacuum degassing function.

〔Example〕

Regarding continuous refining equipment having the configuration shown in the figure,
After conducting various preliminary studies, we conducted continuous refining of stainless steel, and found that in order to ensure production of 50't/90 minutes, we would need to use a converter or less in the form of a smelting reduction furnace.
As a decarburization furnace, it is less than a converter, making it extremely compact!・We confirmed that the system can function satisfactorily with appropriate equipment.

〔Effect of the invention〕

By implementing the present invention, $1? The smelting equipment does not require electricity, can use the chromium source in a molten state, and is extremely compact, yet provides processing equivalent to or better than conventional equipment. If it is a continuous refining method that allows you to demonstrate your abilities, /i! rJJ Noh.

[Brief explanation of drawings]

The figure is a schematic diagram for explaining the continuous refining method of the present invention. 1 Melting reduction furnace, 2 Supply lance, 3 Separate lance,
4. Tuyere on the lower side of the smelting reduction furnace 4.5 Inlet, 6. Exhaust port for degassing, 7. Decarburization furnace, 8. Lance of the decarburization furnace, 9. Tuyere on the lower side of the decarburization furnace.

Claims (1)

[Claims] A method in which ore, carbonaceous materials, and lime are added to hot metal in a smelting furnace, and oxygen is blown into the hot metal from either or both of the tuyere installed at the bottom of the furnace and the lance installed inside the furnace to reduce and smelt the ore. In this method, a smelting reduction furnace and a decarburization furnace are connected, and in the smelting reduction furnace, oxygen gas is supplied from a lance, and at least one of oxygen and nitrogen or argon gas is blown from a tuyere in the lower part of the furnace. Lime flux is supplied together with these gases or alone, and ore and carbonaceous materials are supplied from the top, while oxygen is supplied from the lance to carry out a reduction reaction, and pre-treated hot metal is added to the molten metal sent from here. At the same time, it is continuously guided to a decarburization furnace, where oxygen is blown from a lance and gas mainly composed of one or more of argon, nitrogen, and oxygen is blown from the tuyere at the bottom of the furnace to carry out the decarburization reaction. A continuous refining method that consists of adjusting the ingredients.