JPS58100657A - Smelting method for molten high alloy - Google Patents

Abstract

PURPOSE:To recover valuable metals in a high yield without using electric power in a stage for manufacturing a molten high alloy by melting and reducing a starting material contg. valuable metallic oxides, by blowing an oxidizing gas into a molten alloy and by further blowing carbonaceous powder in a state where more than half as much molten slag as the molten alloy is present. CONSTITUTION:For example, semireduced Cr pellets are preliminarily reduced in a rotary kiln 3, charged into a reactor 1 and melted. By blowing an oxidizng gas such as oxygen into the molten metal 7 from tuyeres 2, 10, an exothermic reaction is accelerated, and when the amount of molten slag becomes >=0.5t per 1t molten alloy, a lance 4 is immersed in the molten slag layer 8 to blow carbonaceous powder such as coke breeze or fine coal. Accordingly, the reduction of the Cr pellets is accelerated, and the amount of the molten alloy is gradually increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for smelting a high-alloy molten metal t1 containing a large amount of K elements, such as ferrochrome and 7-eromanganese, by reducing iron, without using electricity.

Ferrochrome, ferromanganese, etc. have traditionally been produced in a low-shaft electric furnace using solid carbon such as coke as the reducing agent and electricity as the reduction energy. This creates strong reducing conditions through the coexistence of solid carbonaceous matter, and heats and heats the products without damaging the strong reducing conditions using electricity.
This is a method of supplying energy. The problem with this method is
There are two points that require improvement:

(1) Electricity as reduction energy is expensive.

It is desirable to be able to supply energy by directly burning solid carbonaceous fuels such as coal and coke.

(2) A commonly used low-shaft electric furnace can only produce high-alloy molten metal whose carbon content is close to the saturated value.

If it were possible to directly produce a medium-carbon high alloy molten metal with a carbon content in the saturation value range of 20 to 80, it would be possible to lower the smelting temperature due to the low melting temperature of the molten alloy, and to eliminate O in the subsequent steelmaking process. CaC2- is known to reduce the carbon burden (compared to normal high carbon ferroalloy production) and is a known dephosphorization/desulfurization method for high alloy molten metal.
Ca F 2-based flux treatment can be applied directly (
High-carbon molten metal has the advantage that it cannot be applied until it is first decarburized and made into a carbon-unsaturated molten metal.
However, if we do not rely on electricity as reduction energy, we must rely on the fermentation reaction for heat generation, which makes it difficult to maintain reducing conditions, and because the carbon in the molten alloy is unsaturated. If so, the activity of carbon, which is a reducing agent, decreases (that is, the reducing power decreases) as an equilibrium relationship of the system.

In order to increase the activity of carbon in contact with the slag, it is possible to add solid carbon to the slag layer, for example, add coke lumps from above the furnace. However, when producing ferrochrome, ferromanganese, etc., there is a large amount of gangue in the raw materials charged into the furnace, so a large amount of slag is generated, and the slag layer is thick, so coke lumps etc. are poured from above. It is desirable that the contact specific surface area (contact area per unit weight of slag) between the slag and solid carbonaceous material be maintained at the required pressure. There is a problem in that it is difficult to sufficiently stir the four slag layers by blowing in the slag, and it is difficult to increase the reduction rate constant.

Therefore, in order to produce a carbon-unsaturated high-alloy molten metal without relying on electric power, the reduction of valuable metal oxides in the slag is generally insufficient.

The present invention is capable of recovering valuable metal components at a high yield without relying on electric power for reduction energy, and can also directly produce carbon-unsaturated high-alloy molten metal if necessary.The gist of the present invention is to: In the process of producing high alloy molten metal by melting and reducing raw materials containing oxides of valuable metals, an oxidizing gas is blown into the molten alloy containing carbon to cause an exothermic reaction, and molten slag is reduced to 0 per ton of molten alloy. .5 or more, carbonaceous powder is blown into the molten slag,
This is a method for smelting high alloy molten metal, which is characterized by reducing valuable metal components.

A detailed explanation will be given below based on specific examples. An example will be explained in which ferrochrome is produced using semi-reduced chromium pellets as a raw material using a bottom-blown converter-like reaction vessel as shown in Figure 1. The reaction vessel IK is equipped with a tuyere 2 at the bottom for blowing oxidizing gas, and oxidizing gas such as oxygen is blown into the molten alloy containing carbon in the reaction vessel, generating heat due to the CO production reaction. let Above the reaction vessel is a device 3 (for example, a rotary kiln) for heating and pre-reducing a mixture of chromium ore and coke and a molded product (for example, pellets) using high-temperature exhaust gas containing CO generated from the reaction vessel. 0 present inventions/
One of the features is that a lance 4 is installed for blowing solid carbonaceous material such as coke powder or coal powder into the molten slag layer. Since this lance is not immersed in the molten alloy layer, it can be a water-cooled lance like a normal oxygen top-blowing lance.

An example of an operation mode using this device is as follows. t
First, the molten alloy should be in a state in which about 50% or less of the rated molten metal amount is present in the reaction vessel. Therefore, K may be charged with molten metal (for example, hot metal) that has been molten in another device, Further, a part of the molten ferrochrome product may remain in the reaction vessel.

IfCa-forming gas is blown into this molten alloy layer as described above to cause decarburization 1 heat generation and stirring. In parallel with this, a molded product of chromium ore as a raw material and coke powder as a reducing agent is heated and pre-reduced in apparatus 3 (semi-reduced chromium (ret)) is charged at high temperature tt from above the furnace. At the same time, lime as a slag-forming agent, coke lumps as a part of a reducing agent, and in some cases semi-reduced chromium □ (once cooled left) are charged from the charging chute 5.

After these are heated and melted in the reaction vessel 1, the chromium oxide and iron oxide are reduced by the carbon content, and the generated Or-F.-C alloy is transferred to the molten metal phase.

The feature of the present invention is that the amount of molten slag is increased, and the molten alloy 1
When the solid carbonaceous powder injection lance 4'fr is immersed in the molten slag layer, coke powder or coal powder is blown into the slag layer. As the carrier gas, an inert gas such as N2 or Ar is suitable. The tip of the lance 4 should be at least 55,051 degrees above the static water level (level when no gas is injected) of the molten alloy in the reaction vessel, and the tip of the lance should not be immersed in the molten alloy layer, and most of the injected solid carbon powder should not be immersed in the molten alloy layer. prevent it from melting directly into the molten metal.

In this state M, the following are involved in the reduction of valuable metal fluoride (chromium oxide and iron oxide in this case) in the molten slag layer.

(a) Solid carbon material introduced from above the furnace (b) Solid carbon material brought in together with semi-reduced chromium pellets (,) Solid carbon material blown into the molten slag layer by lance 4 (d) Into the molten alloy The present invention is characterized by the fact that when the amount of molten slag increases (as mentioned above, 1 ton of molten metal
If the carbon content of the molten alloy is kept unsaturated, the contribution of (a) and (b) will be small, both in terms of equilibrium and velocity (molten slag Unit weight: The contact area between the molten slag and the bath alloy is small)
The feature is that the function of K (e) is added in order to maintain a high reduction rate in situations where the contribution of (d) becomes small.

In this method, the solid carbon powder blown into the molten slag layer is dispersed and acts to quickly reduce the slag, while the carrier gas actively stirs the molten slag layer and indirectly (a), (b), (d) reaction, and also helps transfer the heat generated in the molten alloy layer into the slag layer where reduction energy needs to be supplied, reducing the molten slag both in equilibrium and speed. When the solid carbon suspended in the molten slag comes into contact with the molten metal during the above process, it is partially molten, which is aroused by oxidizing gas and becomes a heat source. It acts as. The level of carbon content in the molten alloy layer can be controlled by adjusting the position of lance 4 (the lower it is, the higher the carbon content) and the amount of carrier (
(The higher the amount of carbon, the higher the carbon content) and the rate of blowing the oxidizing gas into the molten alloy layer. Alternatively, if necessary, carbonaceous powder such as coke may be injected through the tuyere 10 for injecting solid carbonaceous powder attached to the bottom of the reaction vessel 1.

Perform the above operations to gradually increase the amount of molten alloy I. “When the amount reaches a predetermined value, stop charging the raw materials (semi-reduced chromium pellets, etc.), and start blowing oxidizing gas into the molten alloy and into the molten slag. If you want to further reduce the valuable metals (chromium, manzan, iron, etc.) in the slag by injecting carbonaceous solids for a predetermined period of time, then tapping and draining the slag, it is necessary to remove the molten alloy layer before tapping. Stop blowing the oxidizing gas into the molten slag layer, and while stirring with an inert gas such as Ar, change the material injected into the molten slag layer from a carbonaceous solid to a strongly reducing metal or alloy such as 7erosilicon powder, and continue for a specified period of time. In addition, K, which is transferred to the next operation, is a part of the molten alloy (2
0 to 5 Oqk) may be left in the reaction vessel and the same process may be repeated.

In order to reduce the content of phosphorus and sulfur in the tapped molten alloy, K may be treated by separating the molten slag and then blowing 7 lux of Ca C2-Ca F2 system in a non-oxidizing atmosphere. In this case, A part of CaC2 reacts with the carbon-unsaturated molten alloy to generate metal cm from CaC2-*Ca+2C(1)K, which reacts with P in the molten alloy and is converted by 3Ca+2P-+CaP32. A si-dephosphorization reaction occurs. Desulfurization inevitably progresses in cases of strong reduction where dephosphorization occurs. By selecting the amount of flux added in this process, the P and S contents of the molten alloy product can be reduced to arbitrary values.

Example Using the converter-like reaction vessel shown in Fig. 1, semi-reduced chromium oxide (T, Cr3
4 yo, T, Fe17%, black A reduction car 85916,
T, C: 8.0 'j, both 011 whisper, At20.
Carbon-unsaturated ferrochrome (C: 4.2%) is made from carbon-unsaturated ferrochrome (C: 4.2%) using 81029 carbon fiber, average temperature 1100°C) as raw material.

Cr: 61%, Fe: 32%, 81:0.91. P:
0.02%, 8: 0.005%).

Reaction vessel (rated molten metal amount 4 ot, @ double pipe vane for cumulative injection 2)
0 ke = 02200ONm3/hr・tuyere, outer tube pro/mother 60Nm'Ar・tuyere) remains from the previous tap (C
:3.891. Cr: 61%, Fe: 32%, 810.
9s, P: 0.05ts, 8: 0.01%, Warm 1f16
KWl element is injected into the molten metal at a temperature of approximately 20℃ (20℃), and high-temperature semi-reduction o A'' (
V, f 17 t/hr, lump coke f 3.5
t/hr.

Quicklime was almost continuously fed at a rate of 1.6 t/hr (4 to 5 hours), and semi-reduced chromium (60 minutes after the start of charging, the amount of molten slag was 600 kg/h). At the 9th stage, the lance for coke powder injection was immersed in the molten slag, and the N2 gas was 200 Nm5/11r.
Coke powder (less than 1 mφ, fixed carbon content: 88%) is blown into the coke powder as a carrier. The immersion depth of the lance is raised over time so that it is about 1 m from the still water surface of the molten alloy.At this threshold, the carbon content of the molten metal is within the range of 3 to 6%, and the temperature is 1490 to 1590 °C. It was within range. When the amount of molten alloy reached approximately 40 tons, the charging of semi-reduced chromium pellets, lump coke, and quicklime was stopped at the 9th stage, and after 10 minutes of oxygen injection and coke powder injection using N2 gas, the molten alloy was removed. The blowing into is S1&:0□ to A
Change to r (1100ON/hr, tuyere). ! - and 4
K. After changing the feed from the soaking lance from coke powder to 7erosilicon for 5 minutes, 90% of the molten slag and about 50% of the molten alloy were tapped.

The tapped molten metal is collected in a ladle, drained, and poured into calcium carbide (calcium carbide) with a lid on to prevent outside air from entering.
CaCz: 80%) 12kg/l, fluorite (CaF2
: 88%) 3kg/l mixture 1kAr was dephosphorized and desulfurized by blowing sulfur as a carrier @CaC-Ca
The composition and temperature of the molten metal before and after the F2 flux treatment are as follows.

lit after processing! The fusion metal was cast into a ferrochrome lump.

In the present invention, in order to promote the reduction of valuable metal oxides in the slag in the presence of a carbon-unsaturated molten alloy under smelting reduction conditions in which the amount of molten slag is extremely large, (1) the molten alloy layer and the molten slag layer are , the gas must be blown separately and stirred.

(2) Heat generation is performed by blowing an oxidizing gas into the molten alloy layer, thereby stably lowering the oxygen potential of the atmosphere in contact with the molten slag through the molten alloy layer.

(3) By injecting a part of the carbon content into the molten slag in powder form, the reduction of the slag with carbon is promoted and the added carbon is preferentially not used for carburizing the molten alloy. The key point is to combine the three conditions for existence.

By carrying out this invention, a carbon-unsaturated molten alloy can be produced with a high yield and with a small amount of impurities without using electricity, which has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an example of equipment used to carry out the present invention.

Claims (1)

[Claims] In step 11, which produces a high alloy molten metal by melting and reducing raw materials containing oxides of valuable metals, oxidizing gas is blown into the molten alloy containing carbon to generate exothermic ash, while 1 ton of molten alloy is heated to 1 ton. A method for smelting high alloy molten metal, which comprises blowing carbonaceous powder into the molten slag to reduce valuable metal components when the molten slag is present at a concentration of 0.5 or more.