JPH03257084A - Reduction treatment of fired body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for reducing ceramic tiles and other fired products having reduction coloring properties.

(Prior Art and Problems to be Solved by the Invention) Ceramic tiles and other fired products can be obtained by firing them as they are in various kilns, or by applying a glaze to the surface and firing them.

The color of the fired product thus obtained changes subtly depending on the atmosphere during firing, and especially when fired under a reducing atmosphere, sometimes a rich color or pattern can be obtained.

For this reason, conventionally, when firing a fired product in a kiln, a reducing atmosphere is created and a surface reduction treatment is performed simultaneously with the firing.

This reducing atmosphere is generally created by lowering the air-fuel ratio of the burner than the air-fuel ratio during normal firing, but in reducing firing using such a reducing atmosphere, it is difficult to maintain and control the reducing conditions uniformly. This is extremely difficult, as detailed below.

The reduction of the fired product is performed by depriving the fired product of oxygen. When using a fuel gas containing carbon and hydrogen, the reducing gas used to reduce the fired product is a mixed gas of Go and H gas decomposed by the flame of the burner, in which CO gas is There is a large amount and 1
Although it is relatively stable in a high temperature range of 200℃ or higher, it is unstable if these conditions are not met, and if there is even a small amount of 02, it becomes 002, and as the temperature decreases, it decomposes into C and CO2 due to carbon deposition reaction. If so, it will no longer contribute to the return.

Therefore, when reducing the fired product by creating a reducing atmosphere in the kiln, it is extremely difficult to completely isolate the reducing atmosphere from the external atmosphere such as the atmosphere of the previous and previous processes. It is difficult to ensure a good atmosphere.

The temperature of the fired product during reduction treatment is also an important factor.
It is extremely difficult to uniformly reduce the fired product in such an atmosphere while adjusting the temperature of the fired product.

As described above, in the conventional reduction treatment method for fired products, it is not possible to stably produce a product having a uniform desired reduced color.

(Means for Solving the Problems) The present invention has been made to solve such problems, and the gist thereof is to arrange a burner close to the surface of the fired product at a distance of 15 to 8011 degrees, and to remove the burner from the burner. The reduction process is carried out by directly spraying the reduction flame onto the firing surface after firing.

(Operation and Effects of the Invention) As described above, the present invention is capable of reducing the surface of a fired product by directly spraying the reducing flame from the burner from a close distance onto the fired product immediately after firing, without depending on the reducing atmosphere. The flame blown out from the burner at a certain flow rate allows the reduction process to be carried out in a state where the reduction treatment area is completely isolated from the outside. Therefore, the reduction conditions can be easily controlled, and a fired product with a desired reduced color can be stably and easily obtained.

In addition, in the present invention, since the reducing flame from the reducing burner is directly sprayed onto the surface of the fired product from a close distance to perform the reduction treatment, the surface of the fired product can be partially reduced by considering the arrangement of the flame port of the reducing burner. It is also possible to reduce the

In addition, in the present invention, the distance between the eight and the surface of the fired product is set at 15
The reason why the range is 80 to 80 is as follows. In other words, if the burner is separated from the surface of the fired product by more than 80 mm, the flame flow velocity will become smaller and entrainment of outside air will not be sufficiently prevented, and the reducing effect on the fired product will be significantly reduced, resulting in stable reduction. On the other hand, if the burner is placed closer than 15 mm to the surface of the fired product, the reduction reaction will not proceed sufficiently and the reduction reaction will not proceed. In other words, in the present invention, even if the burner is too close to the surface of the fired product, or even if it is too far away, the desired reduction color cannot be obtained stably. It cannot be processed. In terms of positional relationship with the reducing flame, the burner is positioned so that the surface of the fired product is located within a range of 371° to 7/10 from the flame root with respect to the overall length of the reducing flame, although it varies slightly depending on the burner hole diameter and combustion conditions. It is preferable to let

(Example) Next, in order to further clarify the characteristics of the present invention, examples thereof will be described in detail below.

As shown in FIG. 1, a burner 12 has a large number of burner holes each having a diameter of 3 at a distance from the surface of the fired product 10.
A reducing flame (air amount set to 0.6 with the theoretical value of 1) 14 is sprayed in the atmosphere onto the surface of the fired product 10 at approximately 1200°C immediately after firing, and the distance expression is The degree of reduction on the surface of the fired product was observed with various changes. The results are expressed as GO near the surface of the fired product.
This is shown in Figure 2 together with the change in concentration.

As is clear from FIG. 2, the CO concentration in the flame is high at a distance of 15 to 8011, and the surface of the fired product is well reduced.

It should be noted that the present invention is not limited to the embodiments of this embodiment, and the embodiments can be appropriately selected depending on the fired product, the base material, the material and size of the glaze, the desired color tone, the type of fuel gas and combustion assisting gas, etc. It is something.

For example, in a series of batch firing processes, the present invention can of course switch the heat from a firing burner to a reduction burner immediately after firing to reduce the fired product in a batch manner. A reduction treatment step is provided in which a reducing flame is sprayed onto the surface of the fired product in a moving state immediately after firing, so that the reduction treatment can be performed continuously. In either case, the reduction process is accompanied by an endothermic action, so in the process leading to cooling, there is also the effect of gradually cooling down from the firing temperature, which has the effect of preventing the occurrence of deformation and cracking, and it is easy to ensure quality. It is.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the implementation state of a reduction processing method according to an example of the present invention, and FIG. 2 is a diagram showing experimental results of the same example. 10: Burnt product 12: Reduction burner 14: Reduction flame

Claims (2)

[Claims] (1) A method for reducing a fired product, characterized in that a burner is placed close to the surface of the fired product at a distance of 15 to 80 mm, and the reducing flame from the burner is directly sprayed onto the surface of the fired product after firing. . (2) The fired product after firing the reducing flame from the burner by arranging the burner so that the surface position of the fired product is in the range of 3/10 to 7/10 from the flame root with respect to the entire length of the reducing flame from the burner. A method for reducing a fired product, characterized in that the reduction treatment is carried out by spraying directly onto the surface.