JPS586694B2 - Youyu Silica No Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing fused silica, and more specifically, a method for producing fused silica, in which hydrogen used as a fuel is supplied in excess of oxygen and burned to melt silica stone in a reducing atmosphere. This invention relates to a method for producing fused silica.

Conventionally, fused silica has been produced by methods such as melting silica stone using electric heat or the combustion heat of heavy oil.
According to these methods, impurities such as carbon are mixed into the product, causing color and making it impossible to obtain a high quality product.

Another method is to mix hydrogen and oxygen in chemical equivalent proportions and melt the hydrogen using an oxyhydrogen flame that completely burns the hydrogen. Since the iron contained therein melts in an oxidizing atmosphere, there are drawbacks such as oxidation and coloring of the iron, and a decrease in quality.

Generally, fused silica is obtained by melting high-purity silica stone, such as white silica stone, as a raw material. Usually white silica stone is white in color, but those containing a very small amount of iron have a brown or red appearance. When fused silica is produced using these raw materials, impurities form in layers or spots on the inside or surface of the product, which is unfavorable in terms of quality and appearance.

Due to its low coefficient of thermal expansion, fused silica is used in precision instrument parts, electronic materials, ceramic products, etc. However, when fused silica is processed as a raw material, it has a high aesthetic quality in addition to its physical properties. What is desired is something that has the following.

The purpose of the present invention is to solve these drawbacks, and by melting silica stone in an excess hydrogen state using hydrogen as fuel, the resulting product has a beautiful design. The purpose of the present invention is to provide a method for producing fused silica that can further reduce the amount of impurities by removing the iron content using a magnet when pulverized.

That is, in the present invention, when melting silica powder using hydrogen as fuel, the volume ratio of oxygen to hydrogen is 0.43 to 0.4.
It is characterized in that it is supplied to the furnace at a ratio of 8% and melted in a reducing atmosphere.

The present invention will be further explained in detail below.

In the present invention, when manufacturing fused silica, the amount of hydrogen used as fuel is important, and the hydrogen is supplied into the furnace at a rate that creates a reducing atmosphere in the furnace, and is combusted to reduce the iron content in the silica stone. The purpose is to make it into metal iron.

In the present invention, the capacity ratio of oxygen to hydrogen is 0.43 to
The reason for setting the ratio to 0.48 is that silica powder is melted in a reducing atmosphere, and if the ratio exceeds 0.48, impurities will form in layers or spots inside or on the surface of the fused silica that is produced. If it is less than 0.43, it will be difficult to melt the silica powder.

The melting furnace used in the present invention is a closed type furnace, for example, a device that sprays the raw material powder into the furnace from the upper part while rotating from a nozzle. In this case, even if the bottom part is sealed in the molten material and it can be manufactured continuously,
Alternatively, a discontinuous type may be used in which raw material powder is placed at the bottom and sides to melt the supplied raw material.

The raw material used in the present invention is preferably a highly purified silica stone, such as white silica stone, and a fine powder of about 1 mm or less is sufficient, but since it is rotated from a nozzle, it is preferably as thin as possible.

Since the melting point of silica stone is 1,670°C, the melting temperature may be higher than this temperature, but in the present invention, the melting temperature is 1,700°C to 1,700°C.
The temperature is 2000°C, preferably 1850 to 1950°C.

As explained above, the present invention is a method for producing fused silica by burning and melting silica powder in an excess hydrogen state,
According to the method of the present invention, the trace amount of iron in the silica stone is not oxidized, but rather becomes metallic iron, so molten silica can be used as is.
Even when used, there is no problem in terms of appearance, and when it is crushed into a fine powder, it has the advantage of being able to be separated using a magnet or the like.

The present invention will be further explained below with reference to Examples.

Example Appearance: Two types of domestic white silica stone with brown or red appearance (analysis value Si02 99.7%, Fe203 respectively o.o.
The ratio of oxygen to hydrogen is 0.33, 0.43, 0.45, 0.48 in volume ratio for os% and 0.010%, respectively.
, 0.5, and melted in a discontinuous fused silica melting furnace at a temperature of 1900° C. for 5 minutes.

As a result, in the case of volume ratios of 0.43, 0.45, and 0.48, no layered or speckled impurities were observed inside or on the surface of the fused silica, and the fused silica was white.

Further, when the volume ratio was 0.5, the appearance of the fused silica was brown, and when the volume ratio was 0.33, the melting temperature began to decrease, causing problems in the melting itself.

The fused silica was pulverized in this way and the iron content was removed using a magnet.The iron content was successfully removed in the examples, but no iron content adhered to the magnets in the comparative examples.

Claims (1)

[Claims] 1 In a fused silica manufacturing method in which silica stone with a brown or red appearance is melted using an oxyhydrogen flame, a reducing atmosphere is created using an oxyhydrogen flame burner with a volume ratio of oxygen to hydrogen of 0.43 to 0.48. A method for producing fused silica, characterized by continuously melting silica powder at a lower temperature of 1900° C. or higher.