Diameter: 4.0-6.4 m
Capacity: 0.1-3 million tons/year
Material: limestone, clay, coal powder, slag, metal concentrate, tailings, etc.
The iron ore pelletizing process can be divided into four stages: batching, pelletizing, indurating, and cooling. The grate kiln system is mainly applied for the indurating and cooling stages. It has the features of large scale, continuous, high efficiency, and great sealing.
The grate kiln system consists of three independent machines: traveling grate, rotary kiln, and annular cooler. Operators can separately control the running speed of the three devices. It improves the flexibility of the pelletizing process, that is, the production process can be adjusted appropriately according to the change of raw materials.
AGICO, as a professional iron ore pelletizing equipment supplier in China, provides high-quality grate kiln systems with an annual capacity of 0.1-3 million tons. Besides, we offer EPC projects and equipment customization services. Please feel free to consult!
Grate Kiln System Structure
The grate kiln system adopts a grate-kiln-cooler structure. Its placement order is traveling grate, rotary kiln, and annular cooler. The purpose of this system is to transform green pellets into hardened pellets by a high-temperature induration.
The traveling grate is where green pellets are dried and preheated to a temperature of about 800-900℃. It is a conveyor with a good speed change function, which can maintain the required material layer thickness at a reasonable feeding rate. It has three sections: blast drying area, exhaust drying area, and preheating area. After green pellets entering the traveling grate, they are evenly spread on the grate plate. The hot gas from the rotary kiln and annular cooler transmit heat to green pellets so that the physical water and crystal water in the pellet is dried, and some chemical reactions such as magnetite oxidation, carbonate decomposition, and sulfide decomposition occur.
The rotary kiln is a cylinder connecting the traveling grate and annular cooler. It is mainly used to indurate green pellets. The kiln body rotates around the axis and placed inclined to mix the pellets as well as control the pellet flow speed. Therefore all the green pellets are exposed to the burner flame for the same amount of time. In the rotary kiln, green pellets enter from the higher end and are then indurated at a set temperature. After the induration is completed, they are discharged from the lower end.
The annular cooler is applied to cool pellets just discharged from the rotary kiln so that they can be transported and stored safely.
The pellets just discharged from the rotary kiln can reach a temperature of 1249 ℃. They must be cooled to below 100℃ before they can be stored and transported. The annular cooler is divided into three cooling sections, and each section is equipped with a blower. It can reduce the pellet temperature under 100 ℃ and further oxidize the residual FeO in the pellet. After pellets enter the cooler, they are spread on the grate plate to form a uniform materiallayer. Then, they pass through each cooling zone to complete the cooling process.
Highlights Of Grate Kiln System
|Specification||Inclination(%)||Rotation Speed(r/min)||Drive Mode||Bearing Mode||Block Wheel Mode||Weight(t)|
|Φ4.0×30m||3.5||0.47～1.4||Single-side mechanical drive||Rolling bearing||Single hydraulic block wheel||329|
|Φ5.0×35m||4.25||0.3～1.3||Single-side hydraulic drive||Rolling bearing||Single hydraulic block wheel||635|
|Φ5.9×38m||4.25||0.5～1.5||Both-side hydraulic drive||Rolling bearing||Single hydraulic block wheel||960|
|Φ6.1×40m||4.25||0.45～1.35||Both-side hydraulic drive||Rolling bearing||Single hydraulic block wheel||988|
|Φ6.4×45m||4.25||0.45～1.5||Both-side mechanical drive||Rolling bearing||Single hydraulic block wheel||1084|
|Effective Cooling Area（m²）||50||69||121||150||248|
|Trolley Middle Diameter（m）||Φ12.5||Φ12.5||Φ18.5||Φ22||Φ25|
|Material Layer Thickness（mm）||680||762||760||800||850|
|Double-layer Ash Unloading Valve||9||9||15||16||21|