JPS6154098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In order to produce silicon or aluminum, or an alloy thereof, which has a high affinity for oxygen, the present invention processes an alloy containing at least one of silicon or aluminum as an intermediate material in a shaft furnace. It relates to a method of manufacturing by reducing with carbon using combustion heat.

The affinity of elements for oxygen in practical metals in descending order of activity is magnesium, aluminum, titanium, silicon, manganese, chromium, zinc, iron, etc. Among these metals, zinc and iron are manufactured using shaft furnaces.
Furthermore, it is known that ferroalloys with high concentrations of manganese and chromium are manufactured in foreign countries, and that ferroalloys containing up to 30% silicon can be manufactured.

The method of the present invention was developed based on research aimed at producing an alloy containing a high concentration of silicon or aluminum by thermal carbon reduction in a shaft furnace.

In this research, it is almost impossible to produce these pure metals in a shaft furnace, and it is difficult to obtain an alloy containing more than 50% silicon and aluminum using a well-known method, such as an iron alloy. I understood. Therefore, we decided to concentrate aluminum and silicon from such an alloy. There are some known methods for this concentration.
There are new methods shown in examples below, but whichever method is used, it is important to produce an alloy containing a large amount of silicon and aluminum, and to produce the alloy in a shaft furnace with small equipment and high thermal efficiency of the process. This is an essential condition for factory production. The present invention satisfies this condition.

Unless used to explain conventional methods, the term "shaft furnace" in the text refers to a solid charge that forms a moving packed bed, into which combustion supporting gas is introduced, and the combustion heat of the fuel causes physical and chemical changes. It is defined as a vertical furnace in which the main part is the process that causes Therefore, for example, if an electric furnace for producing silicon or ferrosilicon is equipped with an oxygen-containing gas injection tuyere and the resulting combustion heat supplies the majority of the heat required for the reaction, it is included in this definition.

By the way, as is well known, in a steelmaking blast furnace, which is a typical shaft furnace, iron ore is mixed with coke, which is a lump of carbon, and charged into the furnace. The iron ore is heated to the temperature required for reduction and reduced with carbon monoxide gas and carbon to form iron, which is then melted at high temperatures to form molten pig iron. Carbon can reduce all metal elements from their oxides if the temperature rises to the temperature required for reduction, so if you increase the preheating temperature of the air or add oxygen to the air to increase the combustion temperature, Elements that are more active than iron can also be reduced in a shaft furnace, but the elements mentioned above, which are more active against oxygen than chromium, cannot be reduced with carbon monoxide, and as the activity increases, the temperature of reduction by carbon increases. For example, the temperature for iron is about 700℃, for chromium it is about 1200℃, for silicon it is about 1550℃,
For aluminum, the temperature is approximately 2000°C, and there is a problem in that as the reduction temperature increases, the difficulty of reduction increases.

As a method for facilitating reduction, it is known that for chromium and the like, powder ore and carbon raw material powder are mixed to form a briquette, and this is pre-reduced. Also, silicon
It is also well known that pellets made of a mixture of silica stone and carbonaceous material are used to produce 77% silicon ferrosilicon in an electric furnace. Therefore, a means for bringing carbon and oxide raw materials into close contact to facilitate reduction is, for example, an electric furnace in which the weight ratio of silica stone to carbon is 60:24 of the theoretical ratio for carbon reduction of silica stone. This is an effective method, but if this method were used to produce silicon in a shaft furnace, the weight ratio of silicon to carbon (for reduction + fuel) would need to be approximately 60:120, as carbon is used as fuel. If a large amount of carbon or carbon monoxide resulting from combustion is present in this manner, all of the silicon produced will turn into silicon carbide, which is a stable compound, making it difficult to convert it into silicon again, and this method cannot be applied to shaft furnaces. It was known that Aluminum has almost the same situation.

To prevent the formation of the above carbides, aluminum,
It is theoretically known that it is better to form an alloy so that the activity of silicon is sufficiently reduced. Based on this, we came up with the following method. Iron ore is mixed with aluminum, alumina which is an oxide of silicon, silica or bauxite which is a representative mineral of these, silica sand, and the carbon content necessary for reduction is mixed and crushed, and the necessary caking agent is added to form briquettes. shall be. A multi-layered briquette with a layer of carbon necessary for fuel is charged on the outside of the briquette. In this way, combustion supporting gas containing oxygen is sent from below in the shaft furnace, and the heat of combustion in the outer layer is transferred to the inside, and when reduction occurs in the inner layer, it does not come into contact with excess carbon, so that proper reduction occurs. Dew. Based on this reasoning, we conducted a test to create an iron alloy with less than 50% silicon and aluminum content, and found that the reduction occurred more or less as expected, and a molten iron alloy could be obtained.

Next, we conducted a test to obtain silicon, aluminum, and alloys containing high concentrations of these by concentrating them, and found that when silicon and aluminum are extracted from alloys, the yield of silicon and aluminum extraction is not 100%. It is known that silicon and aluminum are lost along with iron, leading to yield losses. As a countermeasure against this yield loss, the metal residue from aluminum and silicon extraction can be included in the briquette of the inner layer, or grains or powder of the metal residue can be placed in contact with the inner layer, and then the outer layer can be formed mainly of carbon. As a result, it was possible to operate the shaft furnace stably in the same way as when iron ore was used with the same alloy composition, and the above-mentioned problem of yield loss was almost eliminated.

That is, the present invention involves pulverizing and mixing an ore containing at least one of silica and alumina with a carbon raw material to form a briquette, and then adding iron, nickel, copper, or tin, or an alloy containing these as main components, in or around the briquette. The outer layer is further coated with a carbon material to form a double layer, and the double layer briquette is charged into a shaft furnace, and a combustion supporting gas containing high concentration of oxygen is fed from the bottom of the furnace. , reducing the oxides with the high temperature generated by combustion of carbonaceous material to produce a molten alloy whose main components are at least one of silicon or aluminum and at least one of iron, nickel, copper or tin; The present invention relates to a method for reducing silicon or aluminum oxides, characterized by the following.

The reason for specifying the alloy as described above in the present invention will be described below.

When carrying out this method, most of the aluminum or silicon alloys produced by reduction by this method require concentration separation of aluminum and silicon. The alloy material was selected based on the ease of operation of this concentration separation and the stability of shaft furnace operation, and from this point of view, iron, nickel, copper, and tin were selected. In other words, when iron, nickel, and copper are alloyed with aluminum, aluminum can be separated in a post-process using the known monochloride method or lead solvent method, and silicon is alloyed with copper and tin. In some cases, silicon can be separated by cooling it. Furthermore, if a copper alloy containing aluminum and silicon is made using copper among the above metals, silicon and aluminum can be separated in sequence.

Although these four metals are important as one of the main constituents of the alloy, there is no problem in including a third element or necessary accompaniment that enhances these effects. For example, only silicon may be reduced and extracted in a shaft furnace using a copper-aluminum alloy, and the copper-aluminum alloy may be circulated, and conversely, the iron-silicon alloy may be circulated to extract aluminum. The latter is a necessary companion when using bauxite as a raw material for aluminum.

In carrying out the method of the present invention, the briquette is a charge for a shaft furnace, and it is necessary that it has the strength to withstand the weight of the stacked charges. For this purpose, it is preferable that the outer layer is formed mainly of coal, which is previously coked in a coking furnace and then charged into a shaft furnace. Even if it is charged into a shaft furnace without being coked, if it is controlled sufficiently, it will coke in the upper part of the shaft furnace and it can be operated to a certain extent, but there is a drawback that it tends to cause instability in the furnace operation. As the carbon material, the above-mentioned coal is generally used, and the outer layer may be formed using coal containing a portion of highly caking coal, which may be coked. In addition, there is scope for the use of coke powder, pituti, asphalt, etc.

The details of the present invention will be illustrated below in an easy-to-understand manner by way of Examples.

Example 1 Mixed coal containing several types of coking coal including high-strength coal was pulverized to 100 mesh or less, and the same
Mix silica stone crushed to 100 mesh or less in a weight ratio of approximately 1:2, add 5% asphalt emulsion containing 50% asphalt, mix well, and form tablets using a previously prepared 28mmφ x 35mm tin block as a core. Machine it into a 40mmφ x 47mm tablet. then 100
Add 4% of asphalt emulsion to the mixed coal that has been pulverized to a fineness of 40 mmφ x 47 mm, and mix well.
Molding a 50mmφ x 60mm tablet using the mm tablet as a core. The tablets were dried at 120° C. for 2 hours in a low oxygen stream and used as raw material for charging into a shaft furnace.

Using a shaft furnace with an inner diameter of 0.8 mφ and a height of 4.5 m, this raw material tablet was charged at a rate of 1050 kg/h. 150% pure oxygen is pumped through three water-cooled copper tuyeres at the bottom of the furnace.
Feed at the rate of Nm ³ /h. As a result, Si9.4%,
Produces 607Kg/h of tin containing 0.24% Fe and 0.25% Al. This tin alloy is discharged from the furnace at a temperature of approximately 1,600°C, so it is slowly cooled to 800°C in a ladle lined with graphite. Silicon deposited at 800°C is separated through a refractory filter. This silicon has some tin attached to it, so it is washed with molten lead to remove the tin. Approximately 55 kg of silicon can be produced in this way per hour. The obtained silicon is in the form of flakes, and is made into a product as it is or by processing such as remelting. When the molten tin after the furnace is further slowly cooled to about 400°C, a tin alloy containing iron and aluminum precipitates, which is removed and poured into a mold to form the aforementioned cylindrical ingot.

From the top of the shaft furnace, carbon monoxide gas associated with carbon reduction of silica stone and pyrolysis gas associated with dry distillation of coal are generated, with a calorific value of 3360 Kcal/Nm ³ and CO,
Approximately 633 Nm ³ /h of gas containing H ₂ and CO ₂ as main components is obtained.

Example 2 Baked powder 1 made by heating kaolin clay consisting of 40.6% SiO ₂ , 37.1% Al ₂ O ₃ , and 0.61% Fe ₂ O ₃ to 700°C and dehydrating it.
Coal powder made of several types of coking coal, including a portion of highly coking coal
Add 0.45 parts of asphalt emulsion containing 50% asphalt to the total amount by crushing it to 100 meshes or less.
% and mix well with an appropriate amount of water. Furthermore, 0.65 parts by weight of copper grains generated in this process, which will be described later, are added to 1 part of the sintered powder and mixed uniformly to form a 34mmφ×45mm
A cylindrical tablet is molded. Further, the pulverized coal powder was kneaded with 4% asphalt emulsion to form a cylindrical tablet of 50 mmφ x 60 mm using the tablet as a core. After drying this at 120°C for 2 hours, it is charged into a shaft furnace, and partially combusted gas is fed into it from the bottom to dry distill it and turn it into coke.

This coked briquette is fed into a shaft furnace with an inner diameter of 0.8 mφ and a height of 4.5 m at a rate of 585 kg/h, quicklime 20 kg/h is supplied, and pure oxygen is supplied from the bottom of the furnace at a rate of 200 kg/h.
Blow at a rate of Nm ³ /h through three water-cooled copper tuyeres. Gas containing CO as the main component is generated from the furnace at a temperature of approximately 350°C. From the bottom of the furnace, Si24.6%, Al
Copper alloy molten metal containing 24.8% and Fe1.2% 139Kg/h and approx.
Kg/h of slag is taken out every 2 hours by opening the tap. When the molten metal is placed in a ladle lined with silicon carbide, placed in a room filled with inert gas, and slowly cooled to 700℃ while stirring, silicon will precipitate.
When the silicon is filtered through a refractory filter, 24.7 kg of silicon containing 6.9% iron is obtained. Since this has aluminum-copper alloy attached to it, it is stirred in molten lead to remove the copper content. The remaining molten metal is 113.5Kg
Contains 9.3% Si and 30.2% Al. This is charged into a vacuum furnace having the following configuration.

It is an airtight container made of steel plate with a refractory lining, and the lower part is lined with graphite, and a graphite electrode is placed in the center from above to perform resistance heating between it and the graphite crucible. A water-cooled condensation chamber is provided from the top to the side through a coke moving bed for removing impurities, and the end of the chamber is connected to an ejector for vacuum suction. 125Kg inside this vacuum furnace
of magnesia and 70 kg of quicklime. After supplying 225 kg of molten metal for the first stage, the furnace was made airtight, evacuated, and electrically heated. 69kg of magnesium can be obtained by applying 100KW for about 6 hours. The residual metal is
It weighs 177Kg, with 12% Si, 10.7% Al, and the rest copper. This residual molten metal is supplied as droplets onto a water-cooled copper plate, and
Copper alloy particles with a diameter of ~3 mm are used in circulation as described above. The slag generated from the vacuum furnace is approximately 200
Kg, its composition is 35% CaO, 49% Al ₂ O ₃ , and the rest Si ₂ O
and MgO.

Example 3 Al ₂ O ₃ 80.1 obtained by firing bauxite
%, 71% of baked powder containing FeO ₃ 16.2%, SiO ₂ 2.9%,
24% coal consisting of several types of coking coal including 5% silica stone and highly coking coal is blended and pulverized, 4% asphalt emulsion is added, and the mixture is thoroughly kneaded with an appropriate amount of water. To 100 parts of the mixture, 40 parts of the iron alloy particles generated in the process described later are added, mixed well, and formed into tablets of 20 mmφ x 43 mm. Furthermore, the above-mentioned pulverized coal powder was kneaded with 4% asphalt emulsion to form a cylindrical tablet of 50 mmφ×60 mm using the tablet as a core. After drying this at 150℃ for 2 hours, it is charged into a shaft furnace and combustion gas is sent from the bottom to produce a maximum of 1000℃.
It is heated to ℃ and dry distilled to make coke.

The coked tablets were fed into the shaft furnace of Example 2 at a rate of 560 kg/h, and pure oxygen was blown from the bottom of the furnace at a rate of 200 Nm ³ /h through three water-cooled copper tuyeres. Gas containing over 90% CO is generated from the furnace at a rate of approximately 650Nm ³ /h at a temperature of approximately 350°C.

Since iron-aluminum-silicon alloy accumulates in the lower part of the furnace, the tap is opened every two hours to take it out. iron 41
Alloy 330 containing %, 40% aluminum and 19% silicon
Kg is discharged from the furnace at a temperature of approximately 1700℃.

The molten metal is put into a melting furnace filled with inert gas and the lead is melted.
Add 6.8t and elute at 1600℃ with electric heating. Molten lead contains 1.6% aluminum, 0.08% silicon, and 0.03% iron.
%, so once this molten metal is cooled to about 1100℃, most of the silicon iron will precipitate along with a small amount of aluminum, which is removed.If the molten lead is further cooled to 700℃, it will now contain about 1% lead. 80Kg of aluminum is produced. The molten lead is separated and used again for aluminum extraction. Molten aluminum containing a small amount of lead can be placed in a vacuum chamber and electrically heated to over 1500°C to drive out the lead and turn it into pure aluminum.

On the other hand, the residual molten metal obtained by extracting aluminum with lead contains approximately 10% aluminum, 28% silicon, and 62% iron, but this is pulverized as in Example 2 and most of it is returned to the charge.

The three embodiments described above demonstrate the wide applicability of the present invention. That is, in Example 1, raw briquette was used, tin was used as an alloying element, placed in the center of a tablet, and silica stone was reduced to produce silicon. In Example 2, coked briquette was used, copper was mixed as an alloying element in the tablet, and kaolin, which is a compound of alumina and silicic anhydride, was reduced to create a copper-aluminum-silicon alloy. First, silicon was extracted and copper Magnesium was manufactured using aluminum alloy as an intermediate raw material. In Example 3, bauxite was used as a raw material for coked briquette, iron was mixed as an alloying element in a tablet, an iron-aluminum alloy was made, and aluminum was extracted from this using lead.

As described above, the briquette may be coked in advance or may be charged as raw briquette without coking, and the former is preferable from the viewpoint of strength as described above. While the briquettes charged in the shaft furnace descend through the furnace, they are heated by the furnace gas rising from the lower part of the furnace, and the coke reaches a sufficient temperature to melt the metal. The coke in the outer layer retains most of the molten metal droplets and falls near the tuyeres, where they are combusted by the combustion supporting gas containing high concentration of oxygen that is blown in from the tuyeres. It becomes very hot. Due to this high temperature, the silicon and aluminum are reduced by the carbon in close contact and are absorbed by the alloying elements present, immediately forming an alloy. After the coke burns out, the alloy inside is released and accumulates at the bottom of the furnace. Based on the results of actually stopping the furnace during operation and examining the contents after cooling, it is assumed that the reaction inside the furnace is as described above.

``In Examples 2 and 3, the coking furnace is not particularly explained, but in the shaft furnace,
Carrying out coking dry distillation at 1000°C is a well-known technique and will not be described in detail.

Furthermore, regarding the carbon content ratio of the inner layer briquette,
Silica SiO ₂ and alumina Al ₂ O ₃ are reduced to Si,
It has been empirically known that reduction tends to proceed when the amount of carbon used as Al or considerably less than this is added. Furthermore, with such an amount, most of the carbon forms the outer layer, which also satisfies the above-mentioned purpose. This amount of carbon is the estimated amount after coking, and this value is
If the increase is 50%, it will be at exactly the rate at which carbide is generated, and a considerable amount of carbide will be formed in the furnace and in the slag, making furnace operation difficult, but the effect of incorporating metal in contact with the inner briquette remains excellent, making furnace operation difficult. The deterioration is not fatal. 'Next, in principle, silicon or aluminum is separated and extracted from the molten alloy obtained as described above. The methods shown in Examples 1 and 2 are methods that have not been known in the past, but the extraction using lead shown in Example 3 is a method that is known in principle, although the details are different. In addition, the known subchloride method can also be used for aluminum extraction.

In Example 2, a molten alloy was used as an intermediate raw material,
An example of producing magnesium without extracting aluminum was shown. There are a small number of ways to utilize the method of the present invention. In addition, it is also possible to apply the present invention not only to metals but also to the production of trichlorosilane by making a copper-silicon alloy and reacting hydrogen chloride gas with it.

In all of the examples, pure oxygen is used as the gas flowing into the furnace, but if the oxygen content is less than 50%, it is difficult to raise the temperature necessary for silicon and aluminum reduction, and 70% or more oxygen is usually required. When manufacturing aluminum alloys, an oxygen concentration of 90% or higher is usually used, as it depends on the concentration in the alloy, but if the concentration is not higher, aluminum nitride will be produced as a by-product and cause adhesion in the furnace.

Since the example was an experimental furnace, the components of the gas generated from the top of the furnace were analyzed, and the amount of heat generated was enormous. For example, in Example 3, the latent heat that can be used by burning the furnace top gas generated from the coking oven and shaft furnace is 3.65×10 ⁷ Kcal when producing 1 ton of aluminum.
If electricity is generated through a boiler, approximately
15000KWh of electricity can be recovered. Therefore, in factory production, this kind of use is always done,
It is calculated that this electric power is sufficient to cover all the electric power required when Example 3 is used as a production plant, for example.

In this way, the method of the present invention uses a method for producing silicon and aluminum, which could conventionally only be produced at low production efficiency in electric furnaces and electrolytic furnaces, by extracting and separating them from intermediate alloys. This provides a method for producing high-content alloys with high production efficiency using a shaft furnace. It also provides new intermediate raw materials for products manufactured from silicon, aluminum, and their high alloys.
Furthermore, the method of the present invention does not consume a large amount of electricity, and the amount of coal consumed is significantly lower than when generating electricity using coal as fuel and using this electricity to manufacture silicon, aluminum, or their alloys. That is, in most cases it is energy saving.

Conventional examples of methods for extracting and producing aluminum and silicon using the shaft furnace of the present invention include methods disclosed in JP-A-56-150141 to 3; A reduction smelting method for aluminum characterized by coking a briquette of a mixture of ore powder and coal powder in a non-oxidizing atmosphere and using the coked briquette as a raw material. Stay where you are. In addition, regarding layered briquettes, Tokuko Sho
No. 45-14641 discloses a tablet in which the inner layer is made of silicon oxide and a carbon reducing material, and the outer layer is mostly made of a carbon reducing material, but this briquette is used in an electric furnace and is necessary for reducing silica stone. It contains only a small amount of carbon. For example, the total amount of carbon is 0.4 per 1 weight of silica. On the other hand, the present invention is a briquette used in a shaft furnace, and since oxygen-rich combustion supporting gas is blown into the furnace, a large amount of gas flows inside the furnace, requiring physical strength, and chemically, the outer layer is not suitable for use as fuel. The amount of carbonaceous material blended is sufficiently large to fulfill its role. In Example 1, the total amount of carbon after coking is estimated to be about 1.86 per 1 weight of silica stone. In this way, most of the large amount of carbon forms a coke layer in the outer layer, forming a container that stores the alloy metal until the temperature inside the briquette rises to a high temperature where carbon reduction of silica and alumina takes place. is a major feature. Furthermore, the above two conventional examples are
There is no indication that the briquette contains a specific metal of the present invention that forms an alloy with silicon or aluminum.

The main embodiments and special usage methods of the present invention, which are also shown in the main text, will be listed.

(1) The method described in the claims, characterized in that the residual alloy obtained by extracting and utilizing aluminum and silicon from the alloy produced by this method is recycled.

(2) The method described in the claims, characterized in that the briquette formed in the briquette machine is coked in a coking furnace, and the coke is charged into a shaft furnace for silicon-aluminum reduction.

(3) The method according to item (1), characterized in that aluminum or silicon is separated and extracted from the alloy produced by this method.

(4) The method described in the claims, characterized in that the carbon material is mainly coal mixed with highly caking coal.

Claims (1)

[Claims] 1 Pulverize and mix an ore containing at least one of silica and alumina and a carbon raw material to form a briquette,
Furthermore, iron, nickel, copper, tin, or an alloy mainly composed of these is contained in or around the briquette, and the outer layer is further coated with a carbon material to form a double layer, and this double layer briquette is made into a shaft. Charge into the furnace,
A combustion supporting gas containing high concentration of oxygen is introduced from the bottom of the furnace, and the oxide is reduced by the high temperature generated by the combustion of carbonaceous material, and at least one of silicon or aluminum is combined with iron, nickel, copper or A method for reducing oxides of silicon or aluminum, which comprises producing a molten alloy containing at least one of tin as a main component.