JPS6012992B2 - carbon cement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon cement used for lining a melting furnace, an electric furnace, etc. with carbon blocks.

In lining construction, adjacent carbon blocks are bonded to each other with carbon cement, but in this case construction is usually done at room temperature, so workability is good, and the cement part does not sag or become discolored after construction. thing,
Furthermore, it is necessary that there is little sag or oozing even before the cement is heated and hardened. It is also desirable that the cement hardened portion has excellent hot metal resistance. Conventionally, generally known carbon cement is a mixture of fer/fell resin, etc., and roasted anthracite powder, etc., with the addition of ethylene glycol, etc., if necessary, to give it an appropriate viscosity so that it can be applied at room temperature.

If the viscosity of this carbon cement is adjusted appropriately to make it easy to apply at room temperature, the cement layer will sag or sag as time passes after installation, and this will become more severe as the temperature rises, causing the adhesive function to deteriorate. It becomes unfulfilled.

In addition, the adhesive layer between the carbon blocks becomes uneven, and sometimes gaps are formed partially, which causes the penetration of the hot metal to exceed the permeability of the hot metal. The present invention is a carbon cement that has good workability at room temperature, does not sag or sag after construction, and has excellent resistance to molten iron in the cement portion after firing and carbonization.

Its feature is that carbon cement contains a small amount of ultrafine anhydrous silica particles. That is, the present invention is a carbon cement comprising a mixture of a liquid thermosetting resin, carbonaceous aggregate powder, and a small amount of ultrafine anhydrous silica as a main component, and further containing a solvent if necessary. Suitable thermosetting resins include initial condensates such as phenol resins, furan resins, and urea resins that are liquid at room temperature.

These are diluted with a solvent if necessary to adjust their viscosity depending on the degree of condensation. As the solvent, alcohols such as ethylene glycol, aromatic solvents such as acetone and benzole, coal tar, etc. are used. Further, it is desirable that the resin has a high carbonization rate and is inexpensive, and from this point of view, phenol resin is preferable. Graphite powder, anthracite powder, etc. are used as carbonaceous aggregate powder, and these powders contain about 10
A particle size of 0 mesh or less is suitable.

The ratio of resin and aggregate powder varies depending on the properties of the resin and the base of the solvent, if any.
It is preferable that the viscosity of the qo is about 300 to 70 oise, but since it is desirable to increase the carbon residual rate as much as possible after carbonization, it is not good to have too little aggregate powder. 10 parts by weight to 35 to 10 parts by weight of aggregate powder is preferred.

In this case, the resin liquid is the total amount of resin and solvent when a solvent is added. Next, regarding ultrafine anhydrous silica particles, the particle size is 50 to 300A, and there are SiOH groups on the surface of the particles, and in a static state, the particles form weak hydrogen bonds with each other, causing slippage between the particles. However, when these particles are suspended in a solvent or the like and placed in a state of motion such as fly azure, the hydrogen bonds are broken and they flow more easily, which is a thixotropic property.

The present invention applies the unique properties of silica to carbon cement, thereby reducing viscosity during construction.
This carbon cement has been developed to increase viscosity and stabilize its shape when it is at rest after construction.

This ultrafine particulate anhydrous silica can be produced, for example, by burning silicon tetrachloride.

It is also possible to use ultrafine silica powder, which is generated as dust when metal silicon or ferrosilicon is smelted in an electric furnace. The amount of silica fine particles in carbon cement is 0.5 to 3. % by weight is appropriate.

If it is less than 0.5%, the effect is not sufficient, and if it is less than 3.0%
This is because if the amount is larger than this, the properties of the carbon base material may be impaired.

The resin, aggregate powder, silica powder, and solvent if necessary are thoroughly mixed. In this case, since the silica powder is fine particles, it is uniformly dispersed and the effect appears uniformly. Although the carbon cement of the present invention is mainly composed of the above-mentioned components, a small amount of molasses, etc. may be added thereto.

Nutrium has the effect of improving the permeability of cement into carbon blocks, and also has the effect of alleviating the odor of phenolic resin, so it is desirable to include it during construction. After construction, carbon cement is hardened and then fired to form a carbide layer, but if this part has poor resistance to hot metal, various problems such as penetration of molten iron may occur.

Another major feature of the carbon cement of the present invention is that it is resistant to hot metal. Next, these will be specifically explained by giving examples.

Example 1 10 parts by weight of liquid phenol resin (solid content 87%) (hereinafter, all parts are based on weight), 45 parts of ethylene glycol, 85 parts of graphite powder (60 mesh or less), and 8 parts of nuka were thoroughly mixed, Further, 3.5 parts of ultrafine anhydrous silica (manufactured by Nippon Aerosil ■, trade name: Aerosil) was added and thoroughly mixed to obtain carbon cement.

As a comparative example, a comparative cement was prepared using the same method as above except that anhydrous silica was removed.

Next, the carbon plates were bonded using both, the bonding surfaces were made vertical, the thickness of the bonding surfaces was kept constant, and both plates were fixed in a floating state. The carbon board has a width of 3 melons and a height of 60 mm.
The adhesive layer has a thickness of 1.5 ribs. When both were maintained at 30q○ for 24 hours in this way, the amount of outflow in the case of the present invention was 0.1%, while that of the comparative example was 43%.

Similarly, carbon plates were bonded together, and with both plates fixed, the temperature was raised at 5°C'hr in an inert atmosphere and held at 100,000°C for 2 hours.

When the residual amount after carbonization, that is, the residual rate was determined with respect to the amount of carbon cement used, it was 60% for the present invention and 30% for the comparative example. Example 2 Cylindrical molded bodies (diameter 2 C, length 15 C) were obtained by molding from the same compositions as in Example 1 and Comparative Example.

After drying and curing, this material was heated at a heating rate of 50°C/h for 10
It was raised to 00qo and used as a carbon rod. Next, add this carbon to 135
The carbon rod was inserted 10 degrees from the tip into hot metal (C: 3.5%) held at 0qo, and the carbon rod was rotated at 60 times/min.
A hot metal resistance test was conducted. After the 10 minute test, both were pulled up and the weight loss per unit area was measured; the one of the present invention had a weight loss of 0.10 t/ground, and the one of the comparative example had a loss of 0.12 t/d.
It was a good day.

Claims (1)

[Claims] 1. A carbon cement containing a mixture of a liquid thermosetting resin, a carbonaceous aggregate powder, and a small amount of ultrafine anhydrous silica particles with a particle size of 50 to 300 Å as the main components, and further containing a solvent if necessary.