JPS59126705A - Treatment of molten iron - Google Patents

Abstract

PURPOSE:To increase the reaction efficiency of gaseous Cl2 and to reduce the amount of gaseous Cl2 to be used when gaseous Cl2 is blown into molten cost iron to remove Mn by blowing gaseous Cl2 after diluting it. CONSTITUTION:Gaseous Cl2 is diluted with an inert gas such as N2 or Ar or dry air. The gaseous Cl2 diluted with the diluting gas is blown into molten cast iron to remove selectively Mn from the molten cast iron without reducing the amounts of Si and C. The reaction efficiency of gaseous Cl2 is increased, and the amount of gaseous Cl2 to be used is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing Mn by blowing C1 gas into hot metal, particularly CI! , concerning gas reaction efficiency.

For example, when casting ductile iron castings, in order to obtain high quality products with the necessary structure and properties, the raw material hot metal must have a high 81-C content (specifically, C2,5-4 On the other hand, it is necessary to use a material with a low Mn content.

However, due to resource depletion in recent years, it has become difficult to obtain inexpensive and high-quality steel scraps and foundry waste pig iron as raw materials for cupola blending. We are now in a situation where we have to actively utilize things with dignity.

Therefore, recently, this type of low-grade cast iron hot metal has been reformed, and M
The aim is to develop technical means for removing harmful components such as n and the like for casting, and it is known that blowing C1 gas into hot metal is one of them. In other words, when 0-metal gas is blown into hot metal, chlorine chemically combines with Mn, forming MnC7.
Since Mn is removed by evaporation from the hot metal in the form of low boiling point compounds such as , 0, etc., the size of the parent partner between chlorine and the elements in the hot metal is approximately In > Ti, A/
, Mg > 81, C, harmful component elements such as Mn-Ti and AA' are preferentially reacted and removed, while Sl and C, which are useful component elements of cast iron, are almost completely removed. It also has the advantage of not incurring any impairment losses.

However, one of the points to be improved when carrying out the Mn removal treatment by blowing C1 gas is that the reaction efficiency of C4 gas is poor, that is, the C1 yield υ is low. This is a technical challenge that is required from the viewpoints of both reducing the amount of necessary C1 gas used and increasing the economic efficiency of treatment, and at the same time reducing the amount of toxic CI and waste gas treated as much as possible.

In order to solve such problems, the present invention aims to solve the above-mentioned C1
This is an improved method of hot metal treatment using gas blowing. That is, in the treatment method of the present invention, in order to increase the reaction efficiency between chlorine and Mn in hot metal, C1. Gas is blown into cast iron hot metal, Sl, C
The method is characterized in that Mn is selectively removed from the hot metal without depleting Mn.

According to the research of the present inventor, it has been found that the reaction efficiency is significantly improved when the C/ gas is appropriately diluted with a diluent gas and injected, compared to when the -G/ gas is blown alone. It was done. This is because even if the same amount of Cl gas is blown into the hot metal, the reaction time in the hot metal can be extended by using diluted r4-gas, and also because the reaction time in the hot metal can be extended not only by C(1) gas but also by the diluent gas. This is thought to be due to the effect being exerted.

Cl, N1, which does not react with hot metal, is used as a diluent gas.
Alternatively, it is preferable to use an inert gas such as Ar gas. It is also possible to use dry air. C1. by mixing these diluent gases. As described later, the dilution concentration of the gas is preferably adjusted to a C11 gas ratio of 50 to 90%.

When injecting this diluted CZ-gas into cast iron hot metal, a small amount of Ti, Al or Mg is added to the treated electric iron in advance in order to more reliably prevent depletion of the useful elements sl and C. is also valid. In other words, these elements have a stronger affinity for chlorine than Sl and C, and also have a stronger affinity for oxygen, so unreacted C contained in the hot metal
81 to the right. This is because C forms chlorides and oxides with C, and also preferentially combines with these additional elements.

As a means of blowing diluted C1 gas into cast iron hot metal,
A blowing nozzle such as a graphite tube is immersed in hot metal stored in a processing container such as a ladle, and gas is blown into the hot metal in the form of bubbles. There is a so-called downward blowing means that blows out fine particles. The latter method, which allows the hot metal and gas to mix uniformly, increasing the contact area and lengthening the residence time of the gas, is far more advantageous in terms of reaction efficiency and in preventing a drop in the temperature of the hot metal. .

Next, examples of the present invention will be described together with comparative examples. The table below shows the de-Mnization of cast iron hot metal using various dilutions C1 and gas.
The results of processing are shown below.

The details of the processing conditions are as follows: cupola hot water ingots with Fe-Mn added to adjust the In content were melted in a 200 kg high-frequency induction furnace, and dilution C gas was blown into each ingot through a porous plug in the processing container. It is. In addition, the treatment temperature was 1500'C.

*C1, yield, 9; 20OKg) Mn for molten metal
Converted using the theoretically necessary CI and injection amount (0.2Kp, 008r1f) to remove 0.1%.

As is clear from the test results in Table q above, according to the treatment method of the present invention in which C7l gas is diluted with a diluent gas such as chlorine or ar gas and blown in, compared to the case where conventional C1 gas is blown alone (&tO) compared to.

C/, it can be seen that the yield is improved. For the preferred dilution ratio of C and gas at that time, please refer to Cjis
;so~90%. If this is less than cA's so%, C1, the amount used will be reduced, but C1,
If the blowing time is extended, the yield rate will decrease, and if the blowing time is extended, the temperature of the hot metal will tend to drop significantly (see A1 to A6).On the other hand, if C&90% is exceeded, the excess B C1 will contribute to saving in gas consumption. (See A9.10) In the above example, only the case where an inert gas is used as the diluent gas is shown, but similar results can be obtained when using C1° gas diluted with dry air. . Furthermore, as confirmed from the above table, in the treatment method of the present invention, only Mn can be selectively removed with almost no change in the useful 81 and C components of hot cast iron before and after treatment.
Other writing effects can be achieved.

As explained above, in the hot metal treatment method of the present invention, C1 and gas are blown in to remove Mn, and C1l is removed.

Since the gas is diluted with a diluent gas and blown into the hot metal, the reaction efficiency of the zero stone gas can be increased, saving C1 consumption and reducing the amount of toxic waste gas treated. There is an effect that can be done.

Claims (1)

[Claims] 1. Hot metal characterized by blowing C& gas diluted with diluent gas into cast iron hot metal to selectively remove Mn from the hot metal without depleting Sl and C. Processing method. Z. The hot metal treatment method according to claim 1, wherein an inert gas such as Ar gas or Ar gas is used as the diluent gas. 3. The hot metal treatment method according to claim 1, wherein dry air is used as the diluent gas. 4 81, T1 is applied to cast iron hot metal in advance to prevent C depletion.
, mulch or Mg is added in claim 1,
The method for treating hot metal according to item 2 or 3.