For the sintering of seamless steel pipe plants
, granulation is quite critical. Common granulation methods include two processes: external coke granulation and layer granulation. The former is based on fine high-grade hematite as the main iron ore raw material, and the latter is based on low-grade limonite and high-phosphorus iron ore. Based on the increasing scarcity of high-grade hematite resources. Therefore, the layered granulation technology has received more attention.
As the main process of layered granulation: firstly granulate high-phosphorus or limonite in a high-speed mixing mixer, then send it into a cylinder mixer and mix it with hematite for secondary granulation, and finally with limestone. Coating granulation with coke powder. The particle structure resulting from the layered granulation process is that the porous iron ore is distributed at the center of the particle, while the dense iron ore separates the limestone from the porous iron ore as an intermediate transition layer.
In the sintering granulation process, the proportion of mixed limestone, the height of the layer and the humidity of the granulation remain unchanged. In order to avoid deterioration of the gas permeability of the sintered layer, the proportion of the particle size <4 mm in the coke powder should be controlled to be less than 10%. The SiO2 content and the alkalinity were controlled to 5% and 1.9, respectively, by controlling the amounts of limestone and quartz.</div>
Layered granulation effect:
1. Influence of high phosphorus iron ore on sintering operation
When the outer coke granulation is increased, the permeability of the super-wet layer does not change significantly with the increase of the proportion of porous high-phosphorus iron ore. However, the gas permeability of the combustion layer is obviously degraded, and the pressure of the entire layer is increased. The increase is increased. The reason is that the fluidity of the liquid phase is deteriorated.
2. Effect of high phosphorus iron ore isolated on the sintering output after particle center
Using layered granulation technology, the liquid phase is not absorbed into the iron ore, the fluidity is improved, and the liquid phase flow length reaches the level of non-phosphorus ore. Due to the enhanced liquidity of the liquid phase, the pore growth of the size of 5 mm or more is promoted, the number is greatly increased, the gas permeability of the combustion layer is improved, and the sintering utilization coefficient is improved.
3. Effect of layered granulation on the quality of sinter ore and blast furnace operation
After applying stratified granulation, the cold strength of the sintered product is better than that of the external rolling method. Mainly caused by the reduction of pores below 5mm. In addition, after the layered granulation process is applied, the low-temperature reduction pulverization of the sinter is slightly improved, and the reduction property is remarkably improved, so that the furnace condition is applied to the blast furnace and the coke ratio is lowered.
In short, the layered granulation technology of seamless steel pipe plant can effectively improve the utilization rate of sintering, and the requirements for ore grade are relatively loose, which has great promotion and application value.