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It is found that the main components of the rust layer are iron oxide and a small amount of chloride and sulfide. Therefore, the corrosive substances on the inner wall of the kiln barrel are oxygen, sulfur and chloride.
(1) High temperature oxidation causes corrosion of the inner wall of the cylinder
Limonite rotary kiln barrel is usually made of ordinary steel, which is not resistant to high-temperature oxidation. Visible "protective" oxide film is produced at 200 ~ 300 ℃. However, the structure of this oxide film is loose and it is difficult to prevent further oxidation of the metal cylinder, especially at high temperature. For example, the annual oxidation rate of A3 steel is 0.58mm at 400 ℃ and 5.84mm at 600 ℃ The temperature of the cylinder in the transition zone of limonite rotary kiln is usually 300 ~ 400 ℃, or even higher. Therefore, oxidation and corrosion on the surface of the cylinder is inevitable.
(2) High temperature vulcanization corrosion is different from high temperature oxidation corrosion. This kind of corrosion can be carried out under the metal skin. The subcutaneous corrosion commodity contains non oxidized metal. The hot corrosion temperature should be 600 ~ 950 ℃, but in the medium containing strong corrosion, high-temperature vulcanization may occur at about 400 ℃, resulting in corrosion of the inner wall.
(3) High temperature chlorination corrodes the inner wall of the cylinder
It is reported that under high temperature environment, the corrosion of chlorine and chloride on steel is particularly severe. Under chlorination conditions, it will form volatile FeCl3 with low boiling point (324 ℃), and then aggravate the corrosion of limonite rotary kiln barrel.
It is roughly pointed out that in the process of calcining lime clinker in limonite rotary kiln, the atmosphere in the kiln is very complex, and various elements constituting cylinder corrosion almost exist and act together, making the limonite rotary kiln cylinder "overburdened" and corroded.
Hongke heavy industry is a Limonite rotary kiln equipment manufacturer, supplying many series of high-quality and high-yield limonite rotary kiln equipment and related cooler, preheater and other kiln equipment, and bearing the description and construction effectiveness of various large limonite rotary kilns.