- Resistance to high temperatures and thermal shock
- Excellent mechanical strength and abrasion resistance
- Low shrinkage and expansion properties
- Ability to conform to complex shapes and surfaces
- Chemical stability and resistance to corrosion
- Cost-effective compared to other refractory materials
Classification of refractory ramming mix
Refractory ramming mix is made of aggregate and powder, as well as binder. The construction method of refractory ramming mix is ramming forming.
Ramming mix include corundum, high aluminum, silicon carbide, carbon, silicon, magnesium, etc. Like electric furnace bottom ramming mix with silicon carbide, graphite, electric calcined anthracite as raw materials, mixed with a variety of ultrafine powder additives, fused cement or composite resin as a binder made of loose material body.
Because the moisture content of refractory ramming mix is low, and the ramming is strong, the performance is better than that of refractory castable. However, the disadvantage of ramming mix is that the construction speed is very slow, the labor intensity is large, and it may also be replaced by dry vibration material and high quality refractory castable.
But the use of ramming mix is in the melting furnace lining, containing carbon and silicon carbide ramming mix in the blast furnace and iron ditch lining application effect is obvious, even than the traditional iron ditch castable on the service life has been greatly improved. There are hot air cupola bridge and other parts, with zirconium ramming work lining, also obtained good use effect, and there are silicon carbide and silicon ammonia ramming mix some new varieties of ramming mix, the use effect is also very good.
Although there are no refractory ramming mix refractory castable more types, but the use of skimmer and branch ditch, residual ditch use effect is better than castable effect, with the rapid development and development of refractory castable, refractory ramming mix will also have a composite form of ramming mix can be better used in the lining of the kiln.
Properties and use of refractory ramming mix
Compared with refractory castable, refractory ramming mix is semi-dry and loose. Generally, they are not bonded before forming, and only with strong ramming can it have a dense structure.
The strength of refractory ramming mix is relatively low at room temperature before sintering, and the strength is not very high even at medium temperature. The strength of the bond is obtained only after the carbon compounds in the binder are coked when heated.
Compared with castables and plastics, refractory ramming mix have higher stability and erosion resistance at high temperature. However, the service life of them, in fact, depends on the pre-burning before use or in the first sintering amount. If the heating surface of the ramming mix is sintered as a whole without cracking and without stratification with the bottom layer, the use effect will be improved a lot.
If the refractory ramming mix is constructed at room temperature, the thermoplastic organic material that can form carbon bond can be used as the binder. The method of hot mixing can be used to immediately construct the mixture after mixing evenly.
After they are formed, different heating methods are used to harden or sinter the ramming mix according to the strengthening characteristics of the mixture. For inorganic chemical binder, self-hardening up to a considerable hardness after the film baking. For the thermoplastic carbon binder, after cooling strength and then demoulding. Reheat to cooker after stripping. If you don’t have a hardened binder at room temperature. To be sintered after ramming, such as the use of silicon ramming mix, it is necessary to boric acid, and then fill the mixed mold and ramming. Then heat sintering, ramming furnace lining sintering can be carried out before use. It can also be finished by heating the first time it is used.
Refractory ramming mix are mainly used as lining materials in smelting furnaces where molten materials are in direct contact. It can be used as a whole furnace lining, but also can be used to manufacture large products.
Tips for ramming mix construction:
Refractory ramming mix is rammed with tamper or air pick. They should pay attention to uniform force and smooth construction when ramming construction. And they are generally used in kiln parts where refractory brick masonry is not possible or difficult. The construction of them is relatively simple. It is used to fill the gap between furnace cooling equipment and masonry or the filling material for masonry screed.
Preparation for construction
According to the design requirements, the furnace steel structure, reference line and holes and other parts, a comprehensive acceptance, qualified before construction. The construction department should clean up the debris in and near the furnace, and transport the air compressor, construction machinery and scaffolding to the site. The air compressor is powered on and the test run is normal. The following table shows the types and main technical indicators of tampers and pickaxes. It can be directly used for ramming mix construction, ramming can be plastic, the hammer needs to add rubber pad. Construction tools also include dressing knife, seam cutter, breathable bit, wire brush, press film with the same shape as anchor brick and wood wedge used to fix anchor brick, etc.
In the construction process, the various types of work should cooperate closely. When the ambient temperature is lower than 10, take preventive measures. After the construction starts, it should be carried out continuously without interruption. If it must be interrupted, cover the knotted surface with a plastic sheet to prevent dehydration. If the shutdown time is long and the knotted surface is dry and hard, welcome out the dry and hard layer and brush the bristles with wire brush, then the construction can proceed.
In the construction process, according to the location of the designed expansion joint, the security of the caulking material, the surrounding should be carefully dense.
Construction of refractory ramming mix
The construction of refractory ramming mix is generally rammed with air pick, the wind pressure can not be less than 0.49Mpa, and the surface area of the hammer is 50mm×(50~80)mm×80mm. Therefore, its impact energy and impact frequency is relatively large.
Ramming, each time the thickness of the material is 20~60mm, the pick should be vertical ramming with the material surface, and should quickly move in one direction, and make the hammer surface overlap about 1/3. The hammer face should be overlapped between each line and between lines to avoid missing knotting. Each layer of material is rammed 3 to 5 times. After forming a dense whole, the ramming surface is bristled, and then the next layer of material can be laid and rammed, and so on. The function of raking is to make the upper and lower layers close together and prevent delamination. The ramming construction should be carried out continuously. If there is a break, the ramming surface should be covered strictly with plastic film to prevent dehydration. Reconstruction, must be raking or chisel into the shape of a ladder, before construction.
Blast furnace discharge groove ramming mix has the characteristics of high volume density, moderate and high temperature strength, strong erosion resistance, erosion resistance, non-stick slag iron, convenient construction, etc. No baking ramming mix do not bake after construction, and no smoke in the process of use, long service life. Suitable for large, medium and small blast furnace iron ditch production needs. Because the product does not need to bake after construction, greatly saving the furnace ditch repair time, improve the blast furnace ironmaking productivity, save the furnace baking equipment, reduce the labor intensity and workload of the front workers, and then reduce the single consumption of resistant material and iron production costs. Depending on the situation of different blast furnaces, the iron flow capacity is 15,000-35,000 tons.