JPH1025155A - Production of alumina substrate according to sintering or melting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an aluminum ash useful by using a rotating type reactional furnace, reacting the aluminum ash with other minerals or compounds with an induction energy based on an oxidizing reaction of the Al and providing an alumina substrate. SOLUTION: This method for producing an alumina substrate comprises carrying out a reaction of an aluminum ash with other minerals or compounds with an induction energy based on an oxidizing reaction of aluminum contained in the aluminum ash using a rotating type reactional furnace according to a sintering or a melting method. Toxic nitrogen compounds contained in the aluminum ash are detoxified by using the oxidizing reaction at a high temperature according to the method. Since the aluminum powder produces the intense induction energy caused by the oxidation, the induction energy is utilized. The rotating type reactional furnace capable of always changing a reactional zone for the reactants at the high temperature is used in the method. Thereby, damage to a refractory material of the furnace body can be reduced and the reaction can be uniformized to shorten the reactional time. The furnace is advantageous to the retention of a uniform high-temperature state and the maintenance of the denitrifying reaction after completing the sintering or melting reaction. Furthermore, the reactional product is converted into an integrally formed product having a high viscosity to reduce the viscosity of the molten product with decreasing temperature in the furnace. As a result, the rotational frequency is increased to carry out a blooming reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION With the development of the aluminum industry, the amount of aluminum smelt generated has increased in recent years. Although aluminum ash is partially used effectively, most of it is subject to industrial waste disposal, raising serious problems for the future aluminum industry.

[0002] It is an object of the present invention to reform aluminum ash into useful resources without treating industrial waste. With the effective use of the heat generated by the oxidation of aluminum contained in aluminum ash, we manufacture additive materials such as mineral products or compounds and sintered bodies or melts, and refined materials for steel and metallurgy, raw materials for refractory kilns, and Providing raw materials for ceramic raw materials.

[0003] There are many problems inherent in the treatment of industrial waste, such as the problem of disposal sites, social responsibilities such as environmental destruction, and the economic problem of disposal costs. These problems also weaken the structure of the aluminum industry. According to the present invention, aluminum ash which is troublesome for treatment can be completely utilized, and the problem of waste is completely released.

[0004]

2. Description of the Related Art Aluminum ash is produced from the following processes and is completely unnecessary from the aluminum refining process. Furthermore, it raises many problems even when treating waste. Aluminum produced by electrolysis from alumina must have its melting point adjusted in order to improve or improve its characteristic values. , For each application.

[0005] Through the melting step, a compound with nitrogen in the atmosphere and nitrogen in the atmosphere having a strong affinity for aluminum is produced. The main composition of aluminum ash is therefore alumina, and in part also includes oxides of the added alloys. The trouble is the presence of the nitrogen compound AlN as the compound.
When the reaction-generated AlN is treated as waste, it comes into contact with moisture.

Following the reaction of

[0006]

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[0007] Since harmful ammonia gas is generated and an exothermic reaction is involved, a large problem is posed in waste disposal.

In order to treat the above reaction products, time-consuming aging treatment is performed, or a reaction with a large amount of water is forcibly performed. After the reaction is completed, the reaction product is subjected to landfill treatment or the like. Have been. This process is an environmentally unfavorable process because it is the emission of ammonia gas to the atmosphere.
In addition, a method of granulation heat treatment and a method of carrying out ammonia treatment with a method of oxidizing heat treatment and then disposing of the same are also employed.

Further, a method of effectively utilizing Al or alumina in aluminum ash has also been adopted in recent years. It is also used as a heat insulator and a means for heating molten steel utilizing the heat generated by oxidation of Al, as deoxidation of molten steel and slag by Al in the steel refining process. The addition of aluminum ash to the smelting slag is used for the purpose of obtaining the effect of lowering the melting point of the slag or increasing the smelting ability. However, the supply to steel refining always has the problem of nitrogen, which was a harmful component in aluminum refining, inherent. Some of them are also effectively used as cement raw materials after harmful Cl and NH ₃ treatment. In any case, the added value is evaluated to be low, and the fact is that the cost is considerably increased and provided.

[0010]

SUMMARY OF THE INVENTION The present invention is a method for detoxifying harmful nitrogen compounds contained in aluminum ash by means of high-temperature oxidation reaction. If the treatment of the nitrogen compound in the aluminum ash can be carried out, there is no major problem in the treatment. However, although the economic burden has been partially reduced, the burden remains significant.

According to the present invention, a useful new substance can be changed based on the physical properties of aluminum ash. It is to recycle so-called industrial waste.
The useful resource substance synthesized according to the present invention can provide materials for refining in the field of steel and metallurgy. In addition, a wide range of ceramic materials can be considered. In other words, the present invention relates to a method for producing valuable materials from the detoxification treatment of aluminum ash and the characteristics of aluminum ash.

[0012]

Examples of other minerals or compounds described in the claims of the present invention include CaO-based minerals and compounds represented by quicklime and SiO ₂ -based minerals represented by silica stone.・ M of compounds, dolomite, etc.
gO-based minerals / compounds, and the above-mentioned composite minerals / compounds to which Al ₂ O ₃ is added. In this case, the reaction additive with aluminum ash is one kind or two or more kinds of raw materials.
Further, for the purpose of lowering the melting point of the reaction, addition of a flux typified by fluoride is also included in the range.

The following description is mainly based on the reaction with CaO-based minerals and compounds. The melting point of pure alumina is in a high temperature region as high as 2020 ° C. Although the composition of aluminum ash is mainly composed of alumina, a great difference is caused depending on the type of the alloy accompanied by the addition of various alloy base wires.

Table 1 shows the composition ranges of the representative elements of aluminum ash.

[0014]

[Table 1]

[0015] TiO ₂ , Fe ₂ O as other minor components
_3, K from the refining flux of aluminum dregs include, Na,
Cl compound is slightly contained. % Me in the above representative composition
-Al and% AlN components easily produce Al ₂ O ₃ by heating means in an oxidizing atmosphere,
The alumina component is pushed up to a high value. Since it is made of high alumina, its melting point does not reach 2020 ° C., but is in a high temperature region near it.

A feature of the present invention is that aluminum ash having such a high melting point is converted into a low melting point by adding other useful minerals or compounds to the ash. The reaction of the reactant with the aluminum ash is performed in a region accompanied by a strong oxidation reaction of the fine aluminum powder in the aluminum ash.

The oxidation reaction of aluminum powder is shown below.

[0017]

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The generation of intense exothermic energy due to oxidation

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The feature of the present invention also in the claims lies in the reactor. Since the reaction is mainly carried out by the combustion reaction of aluminum powder, it is a matter of course that the reactor is lined with a refractory material so as to withstand a high-temperature reaction, that is, the reaction furnace itself is rotated. Among the types of rotary reactors having heating means, the furnace length and furnace diameter do not matter at all. Therefore, a ring kiln or a rotary kiln with a longer furnace length corresponds to the reactor of the present invention.

The rotary reaction furnace can always change the reaction zone of a high-temperature reactant, so that damage to the furnace body refractory material can be reduced. Further, since the rotation is involved, it is an extremely effective means for making the reaction uniform and shortening the reaction time. Further, after the sintering / melting reaction is completed, it is advantageous to maintain a uniform high temperature state and maintain a denitrification compound reaction. The reaction product is an integrally molded product having a high viscosity, but the viscosity of the product decreases as the temperature in the rotary reactor decreases, so that the lumping can be performed. At this time, increasing the number of revolutions is an effective measure for the equivalent mass reaction, and is convenient as a pretreatment of the next step of crushing.

[0021]

DETAILED DESCRIPTION OF THE INVENTION AND

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the sintering and melting reaction according to the present invention will be described in detail below. Rotary mixing is performed based on a predetermined blend of aluminum ash and finely powdered lime, charged into a high-temperature reactor, and heated by an oil burner. This is heating to induce an oxidation reaction of aluminum. The heating means in this case may be any other method such as a gas burner or an electric heating means represented by arc heating.
In addition, heating directly below the mixed powder raw material may be used.

At this time, the compounding ratio is different depending on the quality of the product provided. For example, considering the case where the purpose is to manufacture steel metallurgy refining materials, when the required grade of high alumina content is a main component, the CaO content is small, and when a low melting point refining material is required,
The O content is as high as 20-50%. However, when the additive ratio with respect to the aluminum ash increases, the Me-
Due to the relationship with the Al value, ie, the reaction energy, there is naturally a limitation.

When the temperature of the powder is heated to 300 to 500 ° C., the oxidation and combustion reaction of the Al powder contained in the aluminum ash starts. This reaction is the thermite reaction itself. At that point, no heating is required. The oxidative combustion of the aluminum powder exhibits self-propagation, and an intense high-temperature reaction reaches the entire charged mixed raw material. At this time, waste gas treatment is important because the oxidation reaction of Al involves intense white smoke. The supply of oxygen and the addition of oxidizing materials into the reactor to promote the reaction promote the sintering and melting of the blended raw materials by measuring the completion of the reaction and by obtaining more rapid reaction heat. This is an extremely effective means.

The vigorous and vigorous high-temperature thermite reaction reaches its end in about 10 minutes. The raw material blended with aluminum ash changes shape, creating a new material with changed physical properties. The temperature of the melt at the end of the exothermic reaction is 1500
Aged in a furnace at a high temperature of １1700 ° C. This period is also important as a detrimental denitrification reaction in the product. During this time, the rotation of the furnace continues. As the furnace temperature decreases, the viscosity of the melt decreases and lumps begin. Accelerating the rotation of the furnace for the purpose of promoting lumping is a very effective means for activating the lumping reaction.

The reaction product, which has been cooled down to a temperature range of 1000 to 1400 ° C. by furnace cooling, is taken out of the furnace and is forcedly cooled and crushed by a cooler to obtain a product. At this time, the product can be discharged in a molten state in the furnace, and rapid cooling with water can be measured.

The embodiment will be described below with actual operation data. The rotary reactor used in the present invention is a ring kiln having the following specifications. Diameter (furnace abdomen maximum diameter) 2100mmφ Furnace length 4700mm Lining refractory material High alumina fired refractory Heating method Oil burner Rotation function With variable speed function

Example 1 The above two raw materials are weighed, stirred and mixed, and the reactor is charged, and the oil burner is heated. 9 minutes after the start of the burner heating, the ignition of the aluminum powder was performed, and the thermite reaction was started. At the same time, the burner heating was stopped. The rotation speed of the furnace at that time was 1.5 rpm. As the reaction progressed, a violent combustion reaction accompanied by generation of white smoke was observed.

Six minutes after the start of the reaction, the oxidation combustion reaction of Al was almost completed. According to the observation in the furnace at that time, the added raw material was in a molten state having a high viscosity. The surface temperature of the product was observed to be high, around 1600 ° C. The product was discharged in the furnace when about 37 minutes had passed for keeping the product in a high temperature state and cooling it in the furnace, and forcibly cooled and crushed in the next step to obtain a target product. From the observation result of the product, it was possible to observe the process of melting and solidification, thereby confirming the proof of the present invention.

Example 2

Example 1 The same pretreatment as in Example 1 is performed, and burner ignition is performed. The time required to reach the thermite reaction was 8 minutes. The reaction time required for the formation required 12 minutes.
The reaction time was longer than in Example 1. This is understood to be a factor related to the amount of charge of the charge. The rotation speed of the ring kiln during this period was 1.5 rpm. The furnace temperature of the product was 160, which was almost the same as in Example 1.
It was observed to be inside and outside 0 ° C. It took 30 minutes for the aging temperature holding and the lumping step, and the discharge from the furnace was measured to obtain a product.
Observation was proved to be a clear melt-solidified product as well. The crystal structure of the product obtained according to the invention has also been established by X-ray diffraction analysis according to the following description.

Example: In Examples 1 and 2, CaO or C
An example of the production of a new product by a sintering / melting method based on blending with aCO ₃ has been reported.
Instead of the O raw material, the addition of silica as a SiO ₂ composition was measured, and Al was obtained by the same process as in the above-described embodiment.
₂ O ₃ —SiO ₂ based minerals can also be synthesized. Production of synthetic mullite (crystal composition: 3Al ₂ O ₃ .2SiO ₂ ), which is a typical composition of the present system, is also possible by the method of the present invention. Further, Al ₂ O ₃ —CaO—SiO ₂
Synthesis of ternary minerals or synthesis of Al ₂ O ₃ —CaO—MgO ternary minerals Synthesis of Al ₂ O ₃ —CaO—SiO ₂ —MgO quaternary minerals is also possible by the method of the present invention.

[0032]

The results of analysis of the product prepared according to Example 1 are as follows. 1) Analysis result of main mineral composition from X-ray diffraction analysis 2) Analysis result of oxide composition

The results are shown in Table 1.

[0033]

[Table 1]

[Table 2]

3) Results of Measurement of Melting Point Approximately 1400 ° C. From the above results, the production method of the present invention confirmed and proved the formation of a low-melting-point substance and a new composition substance.

Further, it was confirmed that the produced substance exerted its function sufficiently as a slag refining material in steel refining. It is widely known today that the refining effect by enriching the steelmaking slag with the alumina composition enhances the desulfurization refining ability and the inclusion refining ability. The refining results obtained by adding the product according to the present invention to the LF refining process as a means for refining high-grade steel will be described below.

Effect of the Addition of the Product of the Invention to the Steel Refining Process Effect: 1 Capacity of the Implemented Arc Furnace 70 Ton Secondary Refining Furnace 70 Ton LF Refining Furnace Addition amount of the product of the present invention Basic unit 4 kg / Molten steel Ton The molten steel discharged from the furnace is subjected to CaO-based slag making in an LF refining furnace. At that time, as an alternative to the flux, the product according to the present invention was added to refine the interfacial reaction between molten steel and slag.

The information obtained from the results was as follows. 1) The steelmaking refining temperature is generally set at 1600 ° C. or outside. On the other hand, since the alumina to be added has a high melting point of 2020 ° C., it takes time to reach the refining reaction. Since the product of the present invention has a melting point in the low temperature range of 1400 ° C. and outside, the reaction and dissolution into the smelting slag can be performed in a short time and a smelting slag excellent in smelting characteristics can be obtained. 2) As a result, the effect of shortening the LF refining time was about 3 minutes. 3) The effect of desulfurization refining, which is a guide for refining, was calculated to be about 25% higher desulfurization capacity than the refining level by the conventional method.

Addition of the product of the present invention to the steelmaking refining process Effect: 2 Addition and refining ability of the product of the present invention under the arc electric furnace and the LF refining furnace similar to the effect 1 described above. Further confirmation was made. In this case, the setting environment is different from the above-mentioned effect: 1, unlike the case of tapping from an arc furnace, the predetermined addition of CaO and the product of the present invention are performed simultaneously in a ladle. The slag was refined. At that time, the basic unit of the product according to the present invention was 4 kg / molten steel Ton.

The information obtained from the results was as follows. 1) The refining slag in the EAF furnace was subjected to sludge removal in advance by a slag method and then shifted to tapping. The time required for tapping was 3 minutes, but the slag slag refining by vigorous stirring power of tapping flow proceeded in the latter half after almost completed in the first half of tapping time as expected. As a result of promoting the interfacial reaction between the molten steel and the slag in the ladle, the desulfurization efficiency was improved by about 30% as compared with the ordinary tapping. 2) From the synergistic effect of the improvement of the desulfurization efficiency and the reduction of LF slag in the next step, it was possible to focus on shortening the LF refining time.

In addition, according to the production method of the present invention, since the synthesis of calcium aluminate can be involved, great hope and prospect can be expected for the development of ceramic materials.

[0041]

Claims (1)

[Claims] 1. A reaction with other minerals or compounds is accompanied by rotation by an energy induced by an oxidation reaction of aluminum ash (the definition of the name is described below) and aluminum contained in the aluminum ash. Method for producing alumina base material by sintering or melting method in a reaction furnace to define aluminum ash: aluminum refining slag generated during aluminum refining or secondary refining, or aluminum alloy or master alloy melting and refining process, or It refers to all the refining slag, such as alumidroth, or the above-described smelting slag, or the residue obtained by classifying and extracting aluminum from aluminum dross.