In addition to the material itself, the construction method is very important for the tapping channel. Now briefly described as follows
1) Ramming forming method
This method is the construction method for the lining of the iron tapping ditch in the past. It is often used on the tapping ditch of small blast furnaces. Now it has gradually developed from manual ramming or air hammer ramming in the 1970s to automatic ramming suitable for different parts. Ramming.
2）Pouring construction method (N-Cast method)
In the late 1970s, Japan developed a pouring construction method. This method is to insert a vibrator into the ditch material to directly vibrate, and the ditch material has more moisture. This method has several advantages:
(1) Part of the residual lining can be retained to improve the utilization rate of the lining material;
(2) The groove lining has uniform structure, low porosity and good durability;
(3) Reduce the labor intensity of workers and improve the on-site construction environment. The disadvantages are large noise and longer drying time.
3) Mandrel vibration molding method (VF method)
a vibrator, and apply pressure to it while vibrating at a frequency of several thousand hertz. The thixotropy of the low-moisture ditch material is used to promote the flow of the refractory material and become dense. The forming mold gradually sinks to form the desired groove shape. The water content of the ditch material used in this method is 4% to 6%. Compared with the ramming method, this method is more efficient, consumes less refractory material, and improves the quality of the tapping channel. However, the denseness of the trench lining on the permanent layer side is relatively poorer than that on the inner mold side.
4) Mandrel dry vibration molding method (SVP method)
The construction machinery of the core mold dry vibration molding method is more complicated. The inner mold plate is equipped with high, medium and low frequency vibrators. After the position is placed, it is vibrated while feeding to build the trench lining. This method uses dry materials for vibration molding, which can be dried quickly without bursting, saving time, and is especially suitable for the use of a single tapping fixed groove. In addition, because there is no moisture, the porosity can be reduced, the compactness can be increased, and the service life of the iron trench can be prolonged.
5) Masonry method of large bricks and prefabricated parts
The iron groove preform is cast in the prefabricated mold according to the shape and size of the iron groove. At present, the method is developing rapidly. It puts all the molding, drying, curing, baking and other processes in the refractory factory to complete. The masonry is also fast, and it can be put into use immediately after production. Very applicable. The advantage is that it can be pre-baked and is not limited by the tapping time, and can ensure that the performance of the castable is not limited by the construction conditions, so as to obtain a high-strength iron trough material and relatively extend the service life of the iron trough. The disadvantage is that the external dimensions cannot be too large, otherwise the baking conditions cannot meet the requirements; another disadvantage is that when used in the iron trench, the seams between the preforms become the weak link of the iron trench.
6) Self-flow pouring
Molding Since France developed self-flowing castables, Japan has studied self-flowing iron trough castables. It does not need to vibrate during construction, relying on the weight and position difference of the material to make the pouring material flow freely to achieve degassing, flattening and compaction. It is a viscoplastic material with a low yield value and a certain plastic viscosity developed based on the principle of rheology. The advantages are:
(1) There is no need to vibrate, and it can be poured densely automatically, which greatly reduces labor intensity;
(2) If pumping technology is used in construction, labor will be reduced and efficiency will be improved;
(3) It is more adaptable than vibrating castable and can be cast in any shape.
7) Iron trench repair method
The lining of the slag line and molten iron line of the blast furnace tapping chute is locally damaged faster, especially when the slag-to-iron ratio is high. For this reason, the ditch lining can be repaired with gunning material to achieve balanced damage and improve the life. Refractory gunning materials for blast furnace tapholes generally use high-aluminum-silicon carbide, Al2O3-SiC-C and mullite-silicon carbide materials. The gunning of the tap chute of the blast furnace is generally carried out after removing the lining residue and iron after tapping. Spraying can be started when the temperature is 400~900℃, or it can be carried out at room temperature. The thickness of the gunning layer is 70~150mm each time it is gunned. The disadvantage is that the gunning material has a large rebound loss, is not dense enough, and is easy to layer.