JP2002003929A - SLAG-MAKING AGENT FOR DEOXIDATION COMPOSED OF ALUMINUM DUST AND SiC - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slag-making agent for deoxidation composed of aluminum dust and SiC used for iron- and steel-making, particularly the aluminum dust containing metallic Al with a small diameter in a low content (e.g. <=10% Al content) and the SiC. SOLUTION: The slag-making agent for deoxidation composed of the aluminum dust and the SiC, has the peculiarity, in which the SiC powder is added into the aluminum dust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deoxidizing slag forming agent comprising aluminum slag (hereinafter referred to as "AlD") and SiC used in steel refining and the like, and more particularly to a low content metal Al having a small particle size. And to a deoxidizing slag-making agent comprising AlD and SiC.

[0002]

2. Description of the Related Art AlD is a slag generated when a metal Al block is melted, and is used for refining steel. It is practically used as a slag-making agent because it can utilize the deoxidizing and exothermic abilities of metallic aluminum contained in AlD and can be used as a source of Al ₂ O ₃ for slag. AlD usually contains fine metal Al of about 10 to 40%. AlD having a relatively large particle size and a high content of metal Al is sieved and redissolved to recover metal Al. But,
Since AlD having a small particle diameter and a low content of metallic Al is oxidized during melting, it is difficult to recover Al, and utilization as AlD is being planned. As a technology of steelmaking and steelmaking utilizing aluminum slag, for example, Japanese Patent No. 1750153 discloses iron-containing powder comprising one or more of steel dust, steel scale, steel smelting slag, and raw material oxide for steel, and aluminum. The mixture with the aluminum-containing powder consisting of slag is poured into molten iron and molten steel to cause an oxidation-reduction reaction between the iron oxide and the metallic aluminum in the mixture, thereby causing steel dust and the like and AlD to become a metal resource. There is described an iron making / steel making method using AlD to effectively reuse as well as increase energy efficiency by reaction heat.

Japanese Patent Application Laid-Open No. 9-67610 discloses an improvement of this method in which an iron-containing powder and an aluminum-containing powder are adhered to each other via a substance serving as a binder, and the mixture is adsorbed on a magnet and conveyed. A method of charging molten iron and molten steel is described. Further, JP-A-11-3500
No. 19 describes a method of adding AlD to a stainless steel scale to recover valuable metals contained in the stainless steel scale in the molten steel when the steel is melted.
In any of these methods, AlD is powdered and kneaded with steel dust or scale and charged into an electric furnace to react metal aluminum with metal oxides (nickel, chromium, iron) and reduce and recover them to metal. Technology. According to these technologies, steel dust and the like and AlD, which have been conventionally treated as industrial waste, can be effectively reused as resources, the amount of industrial waste can be reduced, and energy efficiency can be reduced by the heat of reaction between the two. There is also a merit that can be improved. By the way, in putting the above technology into practical use, AlD having a high metal Al content is required. Because of using low-grade AlD with low metal Al content,
In order to increase the absolute amount of metallic Al, the amount of AlD used must be increased, which increases the amount of work, inevitably increases the amount of slag generated, increases costs, and is not profitable. However, the amount of generation of high-grade (high Al%) AlD is relatively small, and it tends to be difficult to obtain. At present, there is a problem in the treatment of industrial waste due to the large amount of low-grade (low Al%) AlD that has little utility value.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present inventors
As a result of various investigations to effectively use low-grade (low Al%) AlD with low utility value, high-grade A was obtained by adding Si, which has the same deoxidation and heat generation properties as Al, to low-grade AlD.
The present invention was completed as a result of further studies based on the idea of exhibiting a function equivalent to ID, and an object of the present invention is to effectively utilize low-grade (low Al%) AlD to improve industrial waste treatment. Is to solve the problem.

[0005]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising adding SiC powder to AlD.
A deoxidizing slag-making agent comprising ID and SiC, wherein the mixing ratio of AlD and SiC powder satisfies the following formula: [Al] +1.35 [SiC ≧ 30% [Al]: Al content in the slag-making agent (weight ratio) [SiC]: SiC content in the slag-making agent (weight ratio) In these inventions, the SiC powder is used. Is used SiC used for silicon wafer cutting and grinding
It is preferably a waste mainly composed of abrasive grains. That is, in the present invention, low-grade AlD is used as AlD of the same quality as high-grade by using SiC having deoxidation and heat generation similar to Al, and furthermore, silicon wafer is cut and ground as SiC. By using used and discarded SiC abrasive grains for use, it has become possible to improve the practicality in terms of cost. Further, in many cases, Si alone is mixed in the waste SiC for wafer cutting. Si alone can be effectively used as a deoxidizing agent in the same manner as SiC.

As shown in the following formula, SiC has twice the capacity of Al in deoxidizing capacity, and therefore SiC is suitable as an additive for AlD. For example, Fe ₂
It acts on O _{3 as} follows. Fe ₂ O ₃ + 2Al = 2Fe + Al ₂ O ₃ Fe ₂ O ₃ + SiC = 2Fe + SiO ₂ + CO In other words, for 1 mole of Fe ₂ O ₃ , 2 moles of Al is required, but 1 mole of SiC is sufficient, so deoxidizing ability Is twice as large.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. In the present invention, SiC to be added to AlD is not particularly limited, but SiC has been conventionally used as a grinding / polishing agent, and the use thereof for cutting a semiconductor Si wafer has recently been increasing. This waste SiC for cutting contains semiconductor Si as cutting and polishing waste, and is particularly ideal as a deoxidizing agent. This waste product (liquid) is the low-grade Al
Similar to the recycling of D, it has been conventionally landfilled for no use, but can be recycled by the present invention. The amount of SiC added to AlD is determined from the following equation. [Al] +1.35 [SiC] ≧ 30% [Al] in the formula is the Al content (weight ratio) in the slag-making agent.
And [SiC] represents the SiC content (weight ratio) in the slag-making agent. As described above, SiC has twice the deoxidizing ability of Al in molar ratio, but it is 1.35 times in weight ratio. The reason why the content is set to 30% or more is that if the content is less than 30%, the amount of the deoxidizing agent used becomes too large, which is disadvantageous in terms of heat efficiency, work amount and the like. If necessary, the use of a carbonaceous agent (carbon breeze, coke, etc.) is also an effective means.

[0008] As a form of use of the deoxidizing slag-making agent comprising AlD and SiC of the present invention, there is a case where the slag-making agent is previously kneaded with a steel scale or steel dust as a powder, but is used as a briquette (molded product). It is preferable to put it in the reduction period of stainless steel and steel refining, and it is particularly preferable to put it as briquette in the converter operation. There is no particular restriction on the use of the deoxidizing slag agent of the present invention, and it can be used in exactly the same manner as the AlD slag agent. Rather than AlD alone
Since the desulfurization and defluorination effects can be expected due to the surplus effect of adding SiC to the ID, it is more advantageous than the AlD alone. It is advantageous that the added SiC has a fine particle size to be kneaded with a metal oxide-containing treated material (steel scale, dust-containing treated material). However, in order to form into a molded article (briquette, pellet), it is necessary to have a particle size of 10 mm or less. Generally, AlD used for steelmaking is a powder mainly composed of <1 mm, so that the molding strength can be improved by adding SiC of 10 mm or less (preferably 5 mm or less). Binders are also used to ensure sufficient molding strength, and starch, PVA (polyvinyl alcohol), tar, portland cement and the like are generally used.

[0009]

EXAMPLES The present invention is described below by way of examples, but the present invention is not limited to these examples. Example 1 An AlD having the components shown in Table 1 and a SiC having the components shown in Table 2 were used to produce a deoxidizing slag agent comprising AlD and SiC of the present invention. SiC having the components shown in Table 2 is a waste liquid used for cutting a silicon wafer.
That is, a wire saw is used to cut a silicon wafer having a large diameter (φ200 mm or more). At this time, a SiC fine powder and its holding, a processing liquid as an adhesive (an aqueous solution containing oil or higher fatty acid) are used. Is used, and the waste liquid of the used processing liquid contains Si of the wafer cutting waste and iron powder of the wire saw, and the components shown in Table 2 are compositions of the waste liquid. At present, it is discarded as a wire saw slurry, but this was used effectively to produce a deacidifying slag agent.

[0010]

[Table 1]

[0011]

[Table 2]

Since the working fluid and the solid matter have a high water content of about 1: 1 (weight ratio), the water content of the working fluid was reduced to about 30% (weight ratio) using a centrifuge. Al by weight
3 parts of D and 1 part of the dewatered slurry were put in a fret mill and kneaded for about 10 minutes. Immediately after kneading, the mixture was put into a briquette molding machine, formed into a briquette having a size of 32 cm × 32 cm × 25 cm in height, width and height, and put into a hot-air drying furnace (furnace temperature set at 150 ° C.). Drying time about 40 minutes, crush strength 25k
g / cm ² briquettes were obtained. No binder was added during briquetting. (Use result) 18-8 stainless steel 30% AlD briquette (comparative material) and this product are used for melting and refining to reduce Cr ₂ O ₃ in slag just before taking slag into ladle. did. The amount of slag in a 30t electric furnace is about 2.
5 tons and 200 kg / Ch of briquettes were used. Table 3 shows the briquette components and the recovery rates of Cr. SiC-
The recovery rate of Cr of AlD is good, probably because the amount of Si alone is not considered in the metal Al equivalent.

[0013]

[Table 3]

Example 2 In order to recover reusable metals such as nickel, chromium and iron in steelmaking dust, scale and pickling sludge, a reducing agent (carbon breath, 10%, AlD 5%) was added, and water was added. (About 10 to 15%), kneaded into briquettes and put into a reduction furnace. At this time, NH ₄ O was added from the added AlD.
H gas was generated. The generated gas was burned in an incinerator, but the NH ₃ was not completely released due to the natural drying of the briquette. Even after 24 hours from the heat generation, the NH ₃ odor remained, which hindered the operation. In order to suppress NH ₃ gas generation, A
It was possible to avoid the problem of odor by using 1D in advance with a water treatment to remove NH ₃ . However, AlN and Al are partially converted to Al (OH)
₃ and the Al content was reduced to 10.8%, resulting in the necessity of increasing the amount of AlD added to the briquettes. Since now the use of metal AL 30% of AlD by working standards of _{AlN + 3H 2 O = Al (} OH) 3 + NH 3 Al + 3H 2 O = Al (OH) 3 + 1.5H 2 present work, equivalent to that of reducing ability The mixing ratio of AlD and SiC was set to 8: 2. 8 parts of washed AlD (Al = 10.8%) and SiC (S
(iC = 86.1%) was mixed well with the two amounts and used in the production of a product. The workability was good. There was no problem with the operation of the reduction furnace.

[0015]

As described above, in the deoxidizing agent using aluminum slag, the effect of desulfurization and defluorination is synergistically obtained by using SiC together with the reducing and exothermic agent Al. In addition, aluminum slag (AlD) having no use value with Al of 10% or less can be effectively used, and a recycling effect was obtained.

Claims (3)

[Claims] 1. A deacidifying slag-making agent comprising aluminum slag and SiC, wherein SiC powder is added to aluminum slag. 2. The deoxidizing slag-making agent according to claim 1, wherein the mixing ratio of the aluminum slag and the SiC powder satisfies the following equation. [Al] +1.35 [SiC] ≧ 30% where [Al]: Al content in the slag-making agent (weight ratio) [SiC]: SiC content in the slag-making agent (weight ratio) 3. The slag for deoxidation according to claim 1, wherein the SiC powder is waste mainly composed of used SiC abrasive grains used in cutting and grinding a silicon wafer. Agent.