JPS5839756A - Manufacture of mn ferroalloy - Google Patents

Abstract

PURPOSE:To manufacture an Mn ferroalloy while effectively utilizing Mn ore by using MnO-rich slag obtd. by adding Mn ore in slag-minimum or slagless refining in a converter by top and bottom blowing as a starting material for manufacturing a ferroalloy. CONSTITUTION:Molten iron treated to remove Si, P, S, etc. is charged into a top and bottom blowing converter, and after adding Mn ore, slag-minimum or slagless refining is carried out to obtain MnO-rich slag by <=20kg/1ton molten iron. By charging this converter slag into an electric furnace as a starting material for an Mn ferroalloy, silicomanganese (Si-Mn) which is a kind of Mn ferroalloy is manufactured. The Si-Mn is used as a deoxidizing agent for a converter or an alloy component regulating agent.

Description

Detailed Description of the Invention The present invention uses Mn0U Tsuchi slag obtained by adding Mn ore and blowing off Mn to a high level in slag minimum refining or slagless top-down blowing converter refining, as a raw material for manufacturing ferroalloy. It is about how to use it.

When Mn ore in lFe ore is added during iron refining in a converter, pe@ide + Mn oxide in the ore is reduced by CK in molten iron and transferred to molten steel as an F source and Ml1m source. is a well-known fact. However, in conventional converter refining, one of the important objectives is not only to oxidize envy in the steel, but also to remove P, so a large amount of Ca is
31. It is necessary to form O-type eggs. There was a problem that the above slug KIN occurred not only with Pg05 (, but up to Fri and Mboro0.1m FeO and 1nooax-s large (
.

The amount of slag was now required to be as small as possible, ie zero. Therefore, the main purpose of converter refining was narrowed down to the removal of C] and the removal of Si.
, theory S, once PI removal was completed at the hot metal stage, a new hot metal pretreatment technology was developed, and it became possible to reduce the amount of slag in the converter to 20 Kf or less per ton of hot metal.
The refining technology is called slag minimum refining or slagless refining (hereinafter referred to as slagless refining when representatively described), and particularly in top-bottom blowing converters, excellent results have been achieved. However, when Mn ore is added to the main W during slagless refining in a top-down blowing rotary furnace, the MnO content in the slag that is formed becomes extremely high (%).It is impossible to waste this slag. It's the economy.

The present inventors focused on this situation, and as a result of studying the converter slag of MIIOQch, they found that the 1Mn purity was higher than the 1S level, and in some cases reached 20 bags or more.
Research ways to use it effectively.

That is, the present invention provides MR
O) The gist is that lattice slag is fed into an electric furnace as a raw material for manufacturing Mn-based ferroalloy.

Hot metal that has been previously treated to remove Si, P, and S (for example, si≦o, goLP≦o, ogon%S, 4G, 0J
IO1) [What is the oxidation reaction in the steel bath when oxygen blowing is performed with the addition of Mm ore?

IC+02→ICO(1) ZMn +OJ! -2M n O (II), but Mfl and coin are applied in the presence of iron O.
The ghee is as shown in Figure 1).

1st igK view 114 [Under OVm conditions of 1450°C or higher, the free energy of reaction formula α is lower than the free energy of reaction formula ■O, and under the high temperature conditions, reaction formula (I) O is Proceed with priority. So 2C+Og→2
CO(I) 2MnO−+ 2Mn+02 (Iil)0)
The reactions of formula and measurement proceed simultaneously, and eventually C+Mn0-
MflO is reduced by +Mn+CO(IV).

On the other hand, Figure 2.8 shows an example of the behavior of Mn in a steel bath subjected to top-down blowing refining. Immediately after the start of blowing, the amount of Mn decreases rapidly, and the amount of Mn decreases to about 26g6 of the total oxygen planned to be blown. It bottomed out and turned to an upward trend.

There is a phenomenon in which the peak value is reached just before the end of the blow-off period, and then it suddenly drops again. This phenomenon can be explained using the reduction energy shown in FIG. 1 as follows. That is, immediately after the start of blowing, the Mlm originally contained in the steel bath begins to decrease due to oxidation, but as blowing progresses, the steel bath temperature rises and the slag-metal reaction begins. and the first
As explained in connection with the figure, Mml in the steel bath begins to increase as a result of the reduction of MnO taking precedence. However, when C in the steel begins to decrease in the latter half of blowing, there is no competition with the oxidation reaction of C, and Mn11D oxidation proceeds again, resulting in OM in the steel! 1 decreases and reaches a stop. That is, since the Mu oxidation reaction that progresses after the peak increases MIIW, the establishment of high MIl blowstop technology is considered to be a particularly important issue in M@ore addition refining #C. But on the other hand, Ml
An increase in Mm activity was observed due to the addition of lll ore, [C]
≦(In the low-lying region of Lllll, the re-oxidation phenomenon of Mn becomes significant (, ilo).

By the way, problems caused by MIHDJ lag can be avoided in 111. Therefore, it is necessary to search for a method for effectively utilizing the above-mentioned KMaOut slag, and the present inventors have utilized the kiMm purity of 1511 or higher, and in some cases as high as 2011 or higher, as a raw material for the production of Mn-based ferroalloys. That is.

VV:2 manganese (hereinafter referred to as 8i) is a type of Mm-based alloy
-Mu) a, Mm and 814Dl11#70 or higher alloy ferroalloys, which are correctly called Mn-8i series ferroalloys, are manufactured using general KM ferromine ore and high (or medium/low) Hiroyuki) 7 erotic! It is faked by mixing hM porridge, which is produced when ν gun is melted in an electric furnace, as a raw material for S1→-. The present inventors converted all or part of this Mn slag into the above-mentioned MnO
This is intended to replace the Elch slug Kll], and if this is explained according to the logistics flow, it will appear as shown in Figure WC4 (conventional method) and Figure @6. That is, according to Fig. 4, in the past, Mll ore was charged into an electric furnace to produce pe-MnH, and by-product Kyuden Furnace slag was charged with other raw materials into a Kyowa electric furnace to produce 84-Mn. , Fe-MnH and Fe
-41Fi was charged into the converter as a deoxidizing agent or alloy composition adjusting agent. In many cases, converter slag is not used in the method of the present invention, but is subjected to waste treatment by other means. On the other hand, according to the method of the present invention shown in the IIHS diagram, Mlk ore is charged into the above-mentioned converter, MnQ-rich slag is charged into an electric furnace, and 51-M
This 51-Mn is used as a deoxidizing agent or an alloy component adjusting agent for converters as described above.

Next, the gist of the present invention will be explained based on specific examples. Figure 2.8 shows an example of converter blowing.
) Σo, xo Although (MEI) O peak was recognized at the regrettable stage, it was blown down to [C)≦0.10.

(:Mn) decreases rapidly, and in the example of FIG. 8 where the 1Mn activity OaI is low, this tendency becomes even more pronounced.

The composition of the blowstop slag applied in the example of FIG. 2.8 is 9 shown in Table 1, which is obviously rich in MaO, but in the case of FIG. 8 it is @KMxhOu. tj4Mn
In terms of purity, the one in Figure 2 is 20.11! 411 in Figure 1 is 26.61e&').

The converter slag obtained in the example shown in Figure g was mixed with M1m ore, 11 stones, etc. of 1 self-composition from the second Kei in the ratio shown in table @B, and charged into an electric furnace to produce 51-Mn. However, the Mnn yield was 85.7, which was almost the same as the conventional method.

(For a moment) Since the present invention has the above-mentioned requirements, the slag minimum of the converter is 61*, which is the M11 multilayer tube charged when performing slagless refining with top and bottom blowing.

It is possible to provide a new method for the effective utilization of natural resources, so that they can be suitably utilized in the form of converter slag.

[Brief explanation of the drawing]

Figure 1 is a graph showing the reduction energy of Mn and C in the presence of iron, so happy! , Figure 8 shows the inside of the bath in converter refining (
FIG. 4 is a graph showing an example of the change in Mn), and FIG. 4 is an explanatory diagram showing a distribution gate 1 of the conventional method. Applicant: Kobe Co., Ltd. 1ll1 Steel Works 3

Claims (1)

[Claims] 141 Hot metal that has been desiliconized, dephosphorized, and desalted in advance is charged into a top-down blowing converter, and slag minimum refining or slagless refining is performed in which the amount of slag per ton of hot metal is 20 to 9 or less. A method for producing a stone Mn-based ferroalloy, characterized in that MnO-rich sug obtained by adding Mm ore is input as an electric furnace feedstock for producing an Mfi-based ferroalloy.