Grate Kiln
Capacity: 0.1-3 million tons/year
Diameter: 4.0-6.4 m
Customization: support
Certificate: ISO, SGS
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: a traveling grate, a rotary kiln, and an 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 in 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.
Traveling Grate
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 enter 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.
Rotary Kiln
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 is 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.
Annular Cooler
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 material layer. Then, they pass through each cooling zone to complete the cooling process.
Highlights Of Grate Kiln System
Low investment, advanced technology, and full use of secondary energy.
It has strong adaptability to raw materials and their property fluctuation.
The grate kiln adopts a PLC system to realize a centralized interlocking control.
Small noise and there is no dust overflow, which improves the working environment.
The stable and adjustable thermal system improves the induration efficiency and pellet quality.
The rotary kiln body is strictly sealed with less heat loss. It can effectively realize a continuous recovery of heat energy.
The grate kiln system meets the need for large-scale production and is suitable for large and medium-sized pelletizing plants.
Specification
| Rotary Kiln | ||||||
| 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 |
| Annular Cooler | ||||||
| Specification | HLQ-50 | HLQ-69 | HLQ-121 | HLQ-150 | HLQ-248 | |
| Effective Cooling Area（m²） | 50 | 69 | 121 | 150 | 248 | |
| Trolley Middle Diameter（m） | Φ12.5 | Φ12.5 | Φ18.5 | Φ22 | Φ25 | |
| Trolley Quantity | 28 | 28 | 45 | 45 | 40 | |
| Trolley Width（m） | 1.8 | 2.2 | 2.5 | 2.5 | 3.75 | |
| Material Layer Thickness（mm） | 680 | 762 | 760 | 800 | 850 | |
| Air Box | 9 | 9 | 15 | 16 | 21 | |
| Double-layer Ash Unloading Valve | 9 | 9 | 15 | 16 | 21 | |
| Capacity（t/h） | 120 | 134-304 | 270-304 | 310-385 | 630-700 | |
| Cooling Time(min) | 45 | 45 | 45 | 48 | 50 | |
| Main Motor | Model | YPT180L-8 | YTSF160L-6 | YTSF160L-6 | YTSP180L-6 | YTSP200L2-6 |
| Power(kw) | 11 | 11 | 15 | 15 | 22 | |
| Rotational Speed(r/min) | 240-720 | 320-970 | 320-970 | 320-970 | 320-970 | |
| Voltage(V) | 380 | 380 | 380 | 380 | 380 | |
| Traveling Grate | |
| Specification(m) | Capacity(million tons/year) |
| 2.0×30 | 0.3 |
| 2.2×32.5 | 0.4 |
| 2.5×33 | 0.5 |
| 2.8×36 | 0.6 |
| 3.1×36 | 0.75 |
| 3.5×39 | 1 |
| 4.0×42 | 1.2 |
| 4.5×60 | 2 |
| 5.0×66 | 3 |
| 5.5×66 | 4 |
Straight Grate Vs Grate Kiln
Pellets produced by grate kiln system have fewer fine particles, better reducibility, and less compressive strength change. They are continuously mixed in the rotary kiln so that all of them can reach the same temperature. While in the straight grate, pellets at the top of the material layer frequently occur over-indurating phenomenon.
The production capacity of the straight grate is slightly higher than the grate kiln, but the power consumption of the air supply system is large and the production cost is high. Compared with the straight grate, the cost performance and production efficiency of grate kiln are relatively high.
The service life of grate kiln system is long and the dust pollution is small. It can use gas, liquid, and solid fuel for pellet production. The production pollution of the straight grate is large, and the product quality is poor.
