JPH029643B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to iron and steel manufacturing methods in the steel manufacturing industry. [Conventional technology] The technology that has been most effective in saving energy, saving resources, and reducing manufacturing costs in steel manufacturing is:
Recently, it can be said that it is a continuous casting method. In refining, larger refining vessels, top and bottom blowing converters,
The electric arc method increases transformer capacity, operates at high power, uses a large amount of oxygen gas, utilizes the combustion heat of heavy oil and kerosene using a jet burner, shortens the scrap melting time by blowing carbon, ferrosilicon, silicon carbide, etc. Various improvements have been made, including the adoption of the scrap preheating method. However, these improvements have resulted in an increase in the amount of dust, scale, etc. generated, and the effective use of these has become increasingly important. The basic component of these dusts, scales, etc. is iron oxide, which contains a considerable amount of iron, but in addition, steel with a high content of alloying elements such as Ni and Cr, such as stainless steel, is manufactured. Dust, scale, etc. that are sometimes generated also contain these alloying elements. On the other hand, the aluminum slag generated in aluminum smelting is also called aluminum dross, and until now, the effective way to use it has been to separate only those with a high metallic aluminum content by crushing, sieving, etc., and then recycling them. The only option available is to melt the aluminum and recover it. Other types of aluminum slag with a low metallic aluminum content are partially used as a heat insulator for steel ingot feeders used in steel manufacturing and as a slag forming agent to replace fluorite, but most low-grade aluminum slag is It is treated as industrial waste. Since this waste contains aluminum nitride, there is a problem in that ammonia gas is generated when it comes into contact with water. On the other hand, a method has been proposed (Japanese Patent Publication No. 39390/1983) in which scale and aluminum slag are used and lime-based substances are added to produce alumina cement and steel. [Problems to be Solved by the Invention] The steel produced by the method for producing alumina cement and steel according to the invention has a chemical composition as listed in Table 3 as an example in the specification.
Because it has a high carbon content and has not been refined, it cannot be called a finished steel that can be used on its own. Therefore, it cannot be said that alloy components other than iron in the scale are also effectively reused. In addition, a special furnace and electrical energy input device must be installed to cause a chemical reaction between metallic aluminum and iron oxide scale in the aluminum slag. Furthermore, the heat generated by the chemical reaction is not used effectively, and only a portion of it is used to sustain the reaction itself. This can be seen from the description that substances that do not participate in the reaction are added to the raw materials. Therefore, the effective use of the various industrial wastes mentioned above is still not sufficient, and in steel manufacturing facilities, steel dust, steel scale, steel smelting slag, etc. that are constantly generated are being disposed of at great expense for industrial disposal. The current situation is that it is treated as a physical object. In addition, aluminum slag with a low content of metallic aluminum is subject to special treatment before being disposed of, as there are problems with normal disposal as described above. The present invention aims to solve the above-mentioned problems of the conventional technology, and provides a method for manufacturing iron and steel using aluminum slag, which efficiently and effectively utilizes a mixture of powder such as steel dust and powder of aluminum slag. The purpose is to [Means for Solving the Problems] The means adopted by the present invention in order to solve these problems are as follows. A mixture of a powder of 30% or higher and an aluminum slag powder is inserted into the ladle at the same time as the molten iron and molten steel is poured into the ladle, and the heat of the molten iron and molten steel causes the oxides in the mixture to mix with aluminum metal. An iron and steel manufacturing method using aluminum slag, which is characterized by causing an oxidation reaction between aluminum slag. Here, the term "steel dust" refers to the dust generated in the shot blasting process of pig iron, steel manufacturing, or steel products, collected using a dust collector, etc., and includes scales that are difficult to peel off on the surface of steel pieces, rolled materials, etc. Iron oxide recovered from the waste liquid generated during the pickling process with hydrochloric acid, sulfuric acid, etc. for removal can also be used as one of the raw materials in the present invention, similar to dust. These dusts become powdered when completely dried. Steel scale refers to oxidized scale generated during processes such as continuous casting, heating of steel ingots, steel slabs, etc., rolling, or forging. Steel smelting slag is made by cooling and solidifying the slag that covers the surface of molten metal during iron and steel manufacturing processes, and is used after being crushed into an appropriate size. All of these have a chemical composition mainly composed of iron oxides, but in addition to that, they also contain Si, Mn, Ni, which are alloying elements contained in the base steel.
It may also contain Cr or the like. Raw material oxides for iron and steel manufacturing refer to oxides of alloying elements to be added to steel to be manufactured, such as manganese dioxide, nickel oxide, and the like. Aluminum slag is generated on the surface of molten aluminum when metal aluminum is remelted, and is usually in the form of powder. The chemical composition of the aluminum slag used in this method is generally as shown in Table 1, but it is too expensive to separate and recover only this amount of metallic aluminum, so it is not treated as industrial waste. There are many. [Function] Iron oxide in steel dust, steel scale, and steel slag undergoes a chemical reaction with metallic aluminum in aluminum slag and is reduced by heat possessed by molten steel or by heat applied from outside for steelmaking such as electric arc. and becomes metal iron. This iron goes into the iron and steelmaking melt and increases its yield. In addition, steel dust generated in the process of manufacturing steel containing large amounts of alloying elements, such as stainless steel, contains other than iron oxides.
It contains many oxides of alloying elements such as Ni and Cr, but when these are used in the manufacturing of steel containing the same alloying elements, they are reduced by metal aluminum and the alloying elements enter the molten steel. Therefore, the input amount of expensive ferroalloy can be reduced. Raw material oxides for iron and steel manufacturing are similarly reduced by metallic aluminum, and alloying elements enter the molten metal. Furthermore, the aluminum oxide in the aluminum slag and the aluminum oxide produced as a result of the above reaction, together with the lime normally used in iron and steel manufacturing processes,
It has the effect of removing S (sulfur), which is generally harmful to steel. Aluminum metal reacts with iron oxides, oxides of alloying elements, and oxygen gas that is normally blown into the steelmaking process, but all of these oxidation reactions are exothermic reactions as shown in the following equation. 2Al+Fe ₂ O ₃ =2Fe+Al ₂ O ₃ +203.7kcal/mol 8Al+3Fe ₃ O ₄ =9Fe+4Al+802.0kcal/mol 2Al+3FeO =3Fe+Al+210.4kcal/mol 2Al+3MnO =3Mn+Al+124.0kcal/mol 2Al+30=Al+400.0kcal /mol The heat of these reactions is Almost as is, it is used as energy for iron and steel manufacturing, increasing the energy efficiency of iron and steel manufacturing. Furthermore, since the present invention causes this reaction to occur in the ladle, the temperature of the molten steel decreases, whereas the temperature of the molten steel generally decreases because there is no heating means in the ladle. It has the effect of delaying the [Effects] The method according to the present invention can process steel dust, etc. and aluminum slag, which have not been sufficiently used as industrial waste, into conventional iron and steel manufacturing processes without adding any special equipment or external energy. This technology has been effectively utilized to solve waste disposal problems, reuse resources, and improve the energy efficiency of iron and steel manufacturing processes. These effects can be obtained without compromising the safety of conventional iron and steel manufacturing processes and without having any negative impact on the environment. That is, iron or alloying elements produced by reduction by metallic aluminum in the aluminum slag are recovered into the molten metal, and the reaction heat is effectively used as a heat source for steel. Furthermore, in addition to being used as a heat source for iron and steel manufacturing, it is also possible to use this method exclusively for treating steel dust, and in this case as well, it has the effect of greatly contributing to reducing the cost of treating steel dust. . Furthermore, in the present invention, a mixture of powder such as steel dust and powder of aluminum slag is inserted into a ladle to cause this reaction, so that the temperature of molten steel generally increases in a ladle that does not have a heating means. This has the effect that it is prevented from lowering, and there is no need to provide a separate heating means for the ladle. [Examples] Examples of the present invention will be described below. In this example, raw material oxide for iron and steel manufacturing and aluminum slag are inserted into a ladle. Mix 100 kg of aluminum slag, 100 kg of manganese dioxide, and 10 kg of fluorite shown in Table 2,
20 kg of this was stored in paper bags and inserted into the ladle at the same time as tapping from the electric arc furnace to the ladle. The amount of molten steel tapped was 72 tons. Table 3 shows the temperature of molten steel before tapping, the temperature in the ladle 5 minutes after tapping and the difference between them, and the temperature of molten steel in the ladle between the conventional method and the method according to the present invention. This is a comparison of the Mn contents of According to the method of the present invention, the temperature decrease was small, and it was confirmed that manganese components were added to the molten steel.

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Claims (1)

[Claims] 1. A mixture of powder of one or more of iron and steel dust, steel scale, steel smelting slag, and raw material oxides for iron and steel manufacturing and powder of aluminum slag is simultaneously taken up when pouring molten iron and molten steel into a ladle. 1. A method for manufacturing iron and steel using aluminum slag, which comprises inserting the aluminum slag into a pot and causing an oxidation reaction between the oxide in the mixture and metal aluminum using the heat possessed by the molten iron or molten steel.