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7 Characteristics of Acid-Resistant Refractory Castables
Acid-resistant refractory castables are castable refractory materials made with water glass as a binder, acid-resistant refractory aggregates, powders and additives (see refractory castables). In addition to hydrofluoric acid and hot phosphoric acid, it can withstand acid and acid gas corrosion, and its maximum operating temperature is 1200℃.
Characteristics of Acid-Resistant Refractory Castables
Acid-resistant refractory castables that are made of acid-resistant refractory raw materials as aggregates and powders and water glass as a binder and are resistant to acid and acid gas corrosion generally have the following properties.
Refractory and acid-resistant castables are new anti-corrosion materials with strong prestress, composed of potassium silicate as a binder, inorganic molecular materials as a curing agent, and silicate as an acid-resistant filler.
Compared with organic acid-resistant materials, refractory and acid-resistant castables are cheap. In addition to having the same performance of organic acid and corrosion resistance, they also have the unique performance of resistance to corrosion by strong oxidizing media.
The performance is stable in organic and inorganic acids of various concentrations, especially in dilute acid, industrial water, and neutral aqueous solution, no crystalline salt is produced, and it has high impermeability.
Good heat resistance, lining in titanium dioxide rotary kiln, the use temperature is as high as 950℃–1000℃.
The fire-resistant and acid-resistant castable uses a non-toxic curing agent, which is non-toxic to operators and construction personnel. It has been identified by the medical and health department and can be used in food, medicine and other equipment anti-corrosion projects.
It has high mechanical strength and excellent bonding properties, especially in the masonry of granite quick materials, acid-resistant tiles, and the bonding force between porcelain plates and cement is greater than that of the parent body.
It cures at room temperature, is simple to construct, easy to use, easy to transport, and moisture-proof for storage.
The acid-resistant castable refractory has high fluidity, is suitable for construction by pouring method, and is an amorphous refractory material that can be hardened without heating. It is widely used!
Construction Requirements of Acid-Resistant Refractory Castables
Acid-resistant castables are actually very picky about the construction environment. According to professional technicians, the following requirements are set for construction work.
Acid-resistant castables, with a thickness of 10-20 mm, are constructed in sections, with a spacing of 2-3 meters between sections and a width of 15-20 mm. The seams are filled with cement.
Acid-resistant castables can also be used to line granite blocks. The bonding layer and seams are generally 10-15 mm.
The construction requirements of acid-resistant castables are the same as those of kpi cement construction.
Acid-resistant castables can be used for reactors, storage tanks, towers, electrolytic cells, trenches, floors, fermentation tanks, etc. in chemical, light industry, smelting, pickling, petroleum, pesticides, food, electroplating, electrolysis and other industrial sectors. They can be cast or lined. After adding steel bars, they can be used as structural anti-corrosion equipment.
When casting inside carbon steel equipment, the construction surface of carbon steel equipment should be sandblasted to remove rust. When casting inside cement concrete equipment, the oil stains and dust on the surface of the equipment should be cleaned.
The template structure for casting must be tight, accurate in size, and have sufficient rigidity. The height should be 50 cm.
Before construction, the surface of the formwork should be oiled, and then the plastic film should be lined on the surface of the formwork, and the joints should be extended by 5-10 cm.
The mixing container and tools must be clean and dry.
The temperature at the construction site must be above 15°C, and a rain shelter should be built during rainy season construction. The mix ratio of kpi concrete and potassium silicate should be fully mixed. Pour the mixed materials into the formwork and perform manual compaction or mechanical vibration.
The depth of each loading should be 30 cm.
When the ambient temperature is above 35°C, the formwork can be removed in seven days. After removal, it is strictly prevented from impact and local ultra-high temperature welding.
If the load-bearing structure equipment is cast, reinforcement should be designed.
How to Classify the Acid, Alkaline, and Neutral Properties of Refractory Materials
Refractory materials are classified into neutral, alkaline, and acidic properties. Whether it is refractory bricks or refractory castables, they are also divided into these three properties.
Neutral refractory materials are composed of aluminum oxide or carbon. Products include high-alumina, corundum, and carbon refractory bricks and castables.
Acidic refractory materials are refractory materials composed of silicon oxide. Products include silicon and clay refractory bricks and castables. For example, silica bricks, lightweight silica bricks, acid-resistant bricks, clay bricks, acid castables, and acid lightweight castables. Acidic products are mainly used for the lining of kilns such as coke ovens and glass melting furnaces. Clay bricks are weakly acidic, but have good thermal shock resistance and are the most widely used.
Alkaline refractory materials are composed of magnesium oxide and calcium oxide as the main components. Products include magnesium bricks, straight magnesium bricks, magnesium-aluminum spinel bricks, and amorphous castables containing 80-85% or more magnesium oxide. Alkaline materials have strong resistance to slag and iron, and the refractoriness of acidic products is higher than that of neutral products. Alkaline products are mainly used for the lining of kilns in alkaline atmospheres, such as rotary kilns and converters. Among the alkaline refractories, the magnesium dolomite refractory bricks are strongly alkaline, while the chrome-magnesium and forsterite refractory bricks or castables and spinel composites belong to the weakly alkaline refractories.
The neutrality, alkalinity and acidity of refractory materials are mainly distinguished by the main components of the matrix. Acidic refractory materials contain a certain amount of silica. Strongly acidic refractory materials are silica bricks and siliceous castables, which are composed of 94-97% silicon (SiO2). Compared with silica, clay refractory materials have less silicon content (SiO2) and are weakly acidic. Semi-siliceous materials are also in the middle. High-alumina bricks, corundum bricks, high-alumina castables, corundum castables, and mullite castables among neutral materials are materials with an aluminum content of more than 45% and tend to be neutral. Chromium refractory materials are also alkaline and tend to be neutral refractory materials.
All raw materials in refractory materials are basically natural minerals, and they are processed into refractory bricks or castables of different grades according to the grade of the raw materials. Therefore, no matter what kind of properties, they are distinguished by the different proportions of the quality of the main materials.
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