JPS59107016A - Method for obtaining molten metal containing ni for manufacturing stainless steel - Google Patents

Abstract

PURPOSE:To obtain molten metal contg. Ni with high economical efficiency of heat without using a melting furnace by charging cold starting materials including a substance contg. Ni and molten low P iron into a vessel and by blowing fine coal and oxygen from a top blowing lance after adjusting the ratio so as to take out a combustible gas. CONSTITUTION:Cold starting materials including a substance contg. Ni are charged into a vessel, preferably a converter and preheated with a combustible gas. Molten low P iron is charged into the vessel, and by blowing fine coal and oxygen from a top blowing lance, the materials are heated to obtain molten metal contg. Ni. At this time, the ratio between fine coal and oxygen is adjusted so as to take gaseous fuel which can be used to preheat cold starting materials out of the vessel. Ordinary coal can b be used, and the use of an electric furnace or a cupola is made unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for thermoeconomically obtaining N1-containing molten metal in a blowing vessel such as a converter without using a melting furnace such as an electric furnace.

Conventionally, the following three methods are typical for manufacturing Ni--Cr stainless/stainless steel, and most of the cold materials are usually produced using electric power (electric furnace) or cupola.

(11Elo-Vac method; 7Elo-Vac method; 7 After melting most of the cold materials such as Elo-nickel, ferrochrome, stainless steel and ordinary steel scraps in a chemical electric furnace, primary decarburization is performed by blowing oxygen into the molten metal using a lance. After that, decarburization is carried out in a ladle degassing device at a final C% of 1, and after completion of decarburization, vacuum treatment is performed to perform final refining.

(21 AOD method; Most of the cold material raw materials such as 7 eronickel, ferrochrome, stainless steel and ordinary steel scraps are melted in an electric furnace, then transferred to a bottom blowing converter, and combined with ordinary bath pig iron or melted. Then, using a mixed gas of oxygen and argon, the 1Ar102 ratio during crude decarburization was lowered, and the Ar1
02 ratio (Ll) is blown into the molten metal to decarburize it, then Fe-81f is added and Or and Mnn are reduced at a constant rate to adjust to the target components.

(3) LD-VAC method: Most of the refrigerant raw materials? Either it is melted in an electric furnace and combined with hot metal in a converter, or most of the cold material is melted in a kegubola and charged into a converter, and oxygen is injected into the molten metal for rough decarburization, and then it is decarburized in a ladle. Final decarburization is performed using gas equipment.

In this way, the conventional stainless steel manufacturing method uses metal materials,
Most of the raw material is powered by an electric furnace, and a cupola is used as a heat source for foundry coke, and the lubricant melting and energy costs account for a large amount of the manufacturing cost, and the electric furnace and cupola equipment are used as a heat source. I needed it.

Is this the purpose of the present invention? It is possible to use steam coal instead of electric power or foundry coke, which is essential in conventional methods, and to melt stainless steel without the need for electric furnaces or cupola melting equipment. The present invention provides a new method for producing stainless steel in which metal material is extremely thermoeconomically melted in a smelting vessel such as a converter, and in particular, a method for obtaining molten metal.
N1-containing materials such as ferronickel and stainless steel scraps, and if necessary, cold material containing N1-containing materials such as ordinary steel scraps, low P pig iron (de-P hot metal) procured separately, and all containers. Then, the material in the container is charged into a converter, and the amount and ratio are adjusted so that the pulverized coal, oxygen, and all the combustible gas can be taken out of the container. It is characterized by raising the temperature of the material by spraying the powdered coal and oxygen, and furthermore, by using the flammable gas generated by the spraying of the powdered coal and oxygen as a preheating fuel for the refrigerant raw material, further thermal economy can be achieved. It is designed so that it can be used to

According to the method of the present invention, when producing Ni-0r type solid/less steel, a converter is fully applied as a container used in the present invention, and the Ni-containing molten metal in the converter obtained by implementing the present invention is Chromium source metal such as ferrochrome is added to the AOD.
By using the same method as the LD-VACj method and the like, the decarburization reaction is allowed to proceed completely while suppressing the oxidation of Or, thereby making it possible to completely melt stainless steel with a desired composition.

As mentioned above, cold materials are basically Ni-containing materials such as ferronickel and stainless steel scraps, but they can also be mixed with common steel scraps and ores in some cases. It is possible. It is a good idea to remove P in the subsequent process of hot metal mixing with this cold raw material.
Use hot metal.

In the case of normal blast furnace pig iron, is there a process for removing P outside the furnace? The P content Rk in the hot metal is kept as low as possible.

The most characteristic process of the present invention is a melting and heating process in which powdered coal and oxygen are blown into the mixed material of N1-containing cold material and low PW pig charged into a refining vessel, specifically a converter. This is a
It is best to use a top blowing lance. Spraying can be done sparingly using pulverized coal and an oxygen tank, but separate lances can also be used. Nitrogen gas or argon as a carrier gas for pulverized coal lance size? can be used.

In this way, by spraying and supplying oxygen to the powdered coal mixed material, the cold material of the mixed material can be easily dissolved in this container, and the temperature of the hot water can be increased. It turns out that it can be effectively "double up." In this case, the reaction in which the carbon in the sprayed pulverized coal dissolves into the hot metal, and the decarburization reaction due to the oxygen of the carbon originally present in the hot metal and the carbon dissolved from the pulverized coal proceed together, and the temperature of the hot metal increases. This is probably because the temperature can be raised quickly and effectively.

Therefore, by fully utilizing this temperature increase, it is possible to melt not only the refrigerant raw material but also the slag forming agent at the same time. Therefore, it is possible to obtain a clean N1-containing molten metal by adding, as necessary, a slag-forming agent to turn the ash in the coal and the metal and non-metal oxide slag entrained from the refrigerant raw materials. .

This melting and heating process can also be carried out as a process for producing flammable gas. That is, by adjusting the ratio of powdered coal and oxygen when spraying them onto high-temperature molten metal, a combustible gas with a high Co concentration (including H2') can be produced. I can get my throat out. First, if you look at it differently, is this container and high-temperature material inside the container used for coal gasification? Use it. The composition and calorie of this generating furnace gas can be adjusted by controlling the amount ratio of oxygen in the pulverized coal. should be established. In other words, if high carbon ferrochrome or chromium ore is subsequently added to the Ni-containing molten metal to produce Or-Ni stainless steel, a sufficient temperature and carbon content are required to carry out the necessary refining. Therefore, the injection of pulverized coal oxygen in the melting and heating process of the present invention should also be controlled based on these specifications. In any case, sufficient amounts of powdered coal and oxygen are required to completely melt the refrigerant raw materials and at the same time maintain the entire hot water at a higher temperature due to the decarburization reaction. Also, C
It is possible to extract the combustible gas rich in O and contained in H2'.

This by-produced flammable gas has various uses as fuel (C
However, it is effective to use it to preheat the refrigerant raw material or, if possible, to preheat the high carbon ferrochrome that will be added subsequently. For this reason, during the recovery of this flammable gas, the total amount of gas generated during the melting and temperature raising process? It is preferable to lead the fuel gas from the top of the container to a gas purifier, remove fumes and dust, and then store it in a gas holder so that the fuel gas can be taken out from the gas holder as needed.

Figure 1 schematically shows the inflow and outflow of substances when a converter is used as a container, and shows how the fuel gas obtained in the melting temperature raising process is used to preheat the refrigerant raw material. . In other words, is there only one cold material in the converter? The above-mentioned fuel gas in the gas holder is charged and combusted with oxygen as the entire fuel, and the combustion gas is brought into direct contact with the cold material in the converter through the combustion flame [, 1: This is preheated. During this preheating process, the combustion exhaust gas heat exchanger 7 can be removed from the upper part of the converter.
Waste heat through? Dissipate after collection. By carrying out this preheating process, it is possible to reduce the heat source unit for the melting temperature raising process, and at the same time, it is possible to accelerate the tartdown of the cut material, which also reduces the amount of carbon in the molten metal in terms of operation time. It is advantageous from the point of view of adjustment and management, and it is also very advantageous from the point of view of making full use of the calorific value of powdered coal.In this way, according to the method of the present invention, lubricant melting equipment such as conventional electric furnaces and cupolas can be used. [Can you use a stainless steel blowing vessel (converter) as a source of N1 refrigerant even without using it? It is possible to obtain N1-containing molten metal using F, and it is possible to use inexpensive steam coal as a heat source, and its heat can be fully utilized, so it is superior to conventional methods in terms of equipment, heat source materials, and thermoeconomics. This Ni-containing %
Hot water? Stainless/stainless steel can be manufactured economically using this method.

Examples of the method of the present invention will be described below.

Example preheating step 90 was put into a converter with 5US3 [14 steel scraps 14. I.J.
61.1 tons of high carbon ferronickel in the form of
The fuel gas (2
040cal/N Part of 77131 10,300 N
Combustion was carried out using 55 UON m3'y of oxygen in a gas burner, and the contents in the furnace were heated for 445 minutes with this flame. Ta.

Melting and heating process 32.3 t'i of low-P hot metal, whose chemical composition is shown in Table 1, which has been previously subjected to deP treatment, is charged into the converter, and powdered coal ( whose chemical composition is shown in Table 2) 200 mesosh or less 90.8%) 43. i t (dry weight basis) Pneumatically blow with nitrogen gas at 1 and 59,70O
N m'' was blown onto the hot metal in the furnace for 45 minutes through a top-blowing Lanske.

@Table 1 Table 2 In addition, in order to promote the slag of ash and other metals and non-metal oxides in the coal, burnt lime and fluorite are divided into several batches using a charging chute on the converter. It was charged in parts. Is burnt lime included in the charging amount? As a result, 74.9 t of base alloy molten metal with low Cr and high Ni was obtained with the components and temperature shown in Table 3.

At the same time, the flammable gas obtained during the entire period of injecting powdered coal and oxygen gold into the converter was cooled, dust removed, and stored in a gas holder. Stocked fuel gas chemical group 5
y, as shown in Table 4, the amount n s6. soo N
It was m.

The low-Or, high-N1 pace alloy molten metal obtained in this example is removed, S removal treatment is performed after removing the slag, and it is added to a predetermined amount of the removed high-carbon ferrochrome, and all of the oxygen is introduced to decarburize it. , ferrochrome can be sufficiently decomposed by the heat generated by the decarburization reaction, and the desired Or-Ni system can be obtained by using only one converter, or by combining a converter and a broken pot degassing device. It is capable of melting stealth steel.

[Brief explanation of the drawing]

Figure 1 is a process diagram of one embodiment of the non-inventive method. Applicant: Nisshin Steel Co., Ltd.

Claims (1)

[Claims] (IJ Ni-containing material? A cold material containing Ni-containing material and low-P hot metal are charged into a container, and powdered coal and oxygen are passed from a top blowing lance to the materials in the container, and combustible coal and oxygen are released outside the container. A method for obtaining a N1-containing molten metal for stainless steel production, which consists of blowing the material in an amount and ratio adjusted to allow gas to be taken out and raising the temperature of the material. (2) A lubricant raw material kg machine containing a Ni-containing substance is After preheating this raw material by spraying combustion gas fueled with flammable gas onto the refrigerant material in this container, low P hot metal is charged into this container, and then it can be discharged into this container. A method for obtaining a N1-containing molten metal for manufacturing stainless steel, which comprises spraying the material in an adjusted amount and ratio and raising the temperature of the material.